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Code Issues Projects Releases Packages Wiki Activity Actions

Merge branch 'main' into NET-6

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Marcello 2021-09-20 21:38:57 +02:00
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49
Android/Activity.kt.md
View file

@ -50,7 +50,7 @@ class MainActivity : AppCompatActivity() {
### Passing data between activities
In *lauching* activity:
In *laughing* activity:
```kotlin
private fun openActivity() {
@ -58,7 +58,7 @@ private fun openActivity() {
//target to open Intent(opener, opened)
val intent = Intent(this, Activity::class.java)
//pass data to lauched activity
//pass data to launched activity
intent.putExtra("identifier", value)
startActivity(intent) //launch another activity
@ -76,7 +76,7 @@ val identifier = intent.get<Type>Extra("identifier")
### Resources Hooks
```kotlin
R.<resourceType>.<resourceName> //access to reource
R.<resourceType>.<resourceName> //access to resource
ContextCompat.getColor(this, colorResource) //extract color from resources
getString(stringResource) //extract string from resources
@ -98,14 +98,14 @@ in `Activity.kt`:
```kotlin
var element = findViewById(R.id.<id>) //old method
<id>.poperty = value //access and modify view contents
<id>.popery = value //access and modify view contents
```
## Activity Components
### Snackbar
Componed derived from material design. If using old API material design dependency must be set in gradle.
Component derived from material design. If using old API material design dependency must be set in gradle.
In `build.gradle (Module:app)`:
@ -144,10 +144,10 @@ startActivity(intent)
val intent = Intent(Intent.ACTION_SEND)
intent.setType("text/plain") //specifying shared content type
intent.putExtra(Intent.EXTRA_MAIL, "mail@address") //open mail client and precompile field if share w/ mail
intent.putExtra(Intent.EXTRA_MAIL, "mail@address") //open mail client and pre-compile field if share w/ mail
intent.putExtra(Intent.EXTRA_SUBJECT, "subject")
intent.putExtra(Intent.EXTRA_TEXT, "text") //necessary since type is text
startActivity(Initent.startChooser(intent, "chooser title")) //let user choose the share app
startActivity(Intent.startChooser(intent, "chooser title")) //let user choose the share app
```
### App Google Maps
@ -186,21 +186,22 @@ In `AndroidManifest.xml`:
//https://developer.android.com/training/permissions/requesting
//intercept OS response to permission popup
override fun onRequestPermissionResult(requestCode: Int, permissins: Array<out String>, grantResults: IntArray) {
override fun onRequestPermissionResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults)
}
fun checkCallPermission() {
//check if permission to make a call has been granted
if (ContextCompact.checkSelfPermission(context!!, android.Manifest.permission.CALL_PHONE) != PackageManager.PERMISSION_GRANTED) {
// i permission has not been granted request it (opens OS popup, no listener aviable)
ActivityCompat.requestPermissions(context!!, arrrayOf(android.Manifest.permission.CALL_PHONE), requestCode) //request code neeeds to be specific for the permission
// if permission has not been granted request it (opens OS popup, no listener available)
// request code needs to be specific for the permission
ActivityCompat.requestPermissions(context!!, arrayOf(android.Manifest.permission.CALL_PHONE), requestCode)
} else {
call() //if permission has been already given
}
}
@SuppressLint("MissingPermission") // suppress warnig of unhandled permission (handled in checkCallPermission)
@SuppressLint("MissingPermission") // suppress warning of unhandled permission (handled in checkCallPermission)
fun call() {
val intent = Intent(Intent.ACTION_DIAL, Uri.parse("tel: <phone number>"))
startActivity(intent)
@ -230,11 +231,11 @@ recycleView.LayoutManager = layoutManager // assign LayoutManager for the recyc
// handle adapter var containing null value
if (array != null) {
adapter = RecyclerViewItemAdapter(array!!) // valorize adapter with a adaper object
recyclerView.adapter = adapter // assing adapter to the recyclerView
adapter = RecyclerViewItemAdapter(array!!) // valorize adapter with a adapter object
recyclerView.adapter = adapter // assign adapter to the recyclerView
}
// add or remom item
// add or remove item
// tell the adapter that something is changed
adapter?.notifyDataSetChanged()
@ -247,7 +248,7 @@ adapter?.notifyDataSetChanged()
```kotlin
webView.webViewClient = object : WebViewClient() {
// avoid openiing browsed by default, open webview instead
// avoid opening browsed by default, open webview instead
override fun shouldOverrideUrlLoading(view: WebView?, url: String?): Boolean {
view?.loadUrl(url) // handle every url
return true
@ -261,7 +262,7 @@ webView.webViewClient = object : WebViewClient() {
}
Intent(Intent.ACTION_VIEW, Uri.parse(url).apply){
startActivity(this) // open br br owser/app when the website changes to external URL
startActivity(this) // open browser/app when the website changes to external URL
}
return true
}
@ -291,7 +292,7 @@ Import in `build.gradle`:
implementation 'com.android.volley:volley:1.1.1'
```
Perrmissions in `AndroidManifest.xml`:
Permissions in `AndroidManifest.xml`:
```xml
<uses-permission android:name="android.permission.INTERNET" />
@ -299,7 +300,7 @@ Perrmissions in `AndroidManifest.xml`:
### Make the request
Subsequnt requests sould be delayed to avoid allowing the user to make too frequent requests.
Subsequent requests should be delayed to avoid allowing the user to make too frequent requests.
```kotlin
private lateinit var queue: RequestQueue
@ -358,14 +359,14 @@ private fun getJSONArrayRequest(){
override fun onStop() {
super.onStop()
queue?.cancellAll("TAG") // delete all request with a particular tag when the activity is closed (avoid crash)
queue?.cancelAll("TAG") // delete all request with a particular tag when the activity is closed (avoid crash)
}
```
### Parse JSON Request
```kotlin
Response.Litener { response ->
Response.Listener { response ->
var value = response.getSting("key")
}
```
@ -374,19 +375,19 @@ Response.Litener { response ->
### Singleton
Object instantiated during app init and is destroid only on app closing. It can be used for data persistance since is not affected by the destruction of an activity.
Object instantiated during app init and is destroyed only on app closing. It can be used for data persistance since is not affected by the destruction of an activity.
```kotlin
// Context: Interface to global information about an application environment.
class Singleton consturctor(context: Context) {
class Singleton constructor(context: Context) {
companion object {
@Volatile
private var INSTANCE: Singleton? = null
// syncronized makes sure that all instances of the singleton are actually the only existing one
fun getInstance(context: Contecxt) = INSTANCE ?: syncronized(this) {
// synchronized makes sure that all instances of the singleton are actually the only existing one
fun getInstance(context: Context) = INSTANCE ?: synchronized(this) {
INSTANCE ?: Singleton(context).also {
INSTANCE = it
}

4
Android/Adapter.kt.md
View file

@ -26,10 +26,10 @@ class RecipeAdapter : RecyclerView.Adapter<RecipeAdapter.ViewHolder> {
}
}
//adapter contructor, takes list of data
//adapter contractor, takes list of data
constructor(myDataset: ArrayList<Recipe>/*, mContext: Context?*/){
mDataset = myDataset
//mContenxt = mContext
//mContext = mContext
}

14
Android/Gradle & Building.md
View file

@ -18,18 +18,18 @@ android {
}
```
## Distribuiting the app
## Distributing the app
### APK vs Bundle
- APK: android executable, contains all assets of the app (multiplr versions for each device). The user downloads all the assets.
- Bundle: split the assets based on dedvice specs. The users donwloads only the assest needed for the target device.
- APK: android executable, contains all assets of the app (multiple versions for each device). The user downloads all the assets.
- Bundle: split the assets based on device specs. The users downloads only the assets needed for the target device.
### APK generation & [App Signing](https://developer.android.com/studio/publish/app-signing)
- **Key store path**: location where the keystore file will be stored.
- **Key store password**: secure password for the keystore (**to be rememberd**).
- **Key alias**: identifying name for the key (**to be rememberd**).
- **Key password**: secure password for the key (**to be rememberd**).
- **Key store password**: secure password for the keystore (**to be remembered**).
- **Key alias**: identifying name for the key (**to be remembered**).
- **Key password**: secure password for the key (**to be remembered**).
The ketstore identifies the app and it's developers. It's needed for APK generation and releases distribution.
The keystore identifies the app and it's developers. It's needed for APK generation and releases distribution.

6
Android/MapsActivity.md
View file

@ -2,13 +2,13 @@
[Google Maps Docs](https://developers.google.com/maps/documentation/android-sdk/intro)
Activity sould be **Google Maps Activity**.
Activity should be **Google Maps Activity**.
In `google_maps_api.xml`:
```xml
<resources>
<string name="google_maps_key" templateMergeStartegy="preserve", translateble="false">API_KEY</string>
<string name="google_maps_key" templateMergeStrategy="preserve", translatable="false">API_KEY</string>
</resources>
```
@ -63,7 +63,7 @@ class MapsActivity : AppCompatActivity(), OnMapReadyCallback,
mMap.setOnInfoWindowClickListener(this)
// Add a marker and move the camera
val location = LatLng(-34.0, 151.0) // set loaction with latitude and longitude
val location = LatLng(-34.0, 151.0) // set location with latitude and longitude
mMap.addMarker(MarkerOptions().position(location).title("Marker in ...")) // ad the marker to the map with a name and position
mMap.moveCamera(CameraUpdateFactory.newLatLng(location)) // move camera to the marker

12
Android/SQLite.md
View file

@ -31,17 +31,17 @@ class DatabaseHelper(
Make data persistent.
```kotlin
class AppSingleton consturctor(context: Context) {
class AppSingleton constructor(context: Context) {
var dataabse: SQLiteDatabase? = null // point to database file in memory
var database: SQLiteDatabase? = null // point to database file in memory
companion object {
@Volatile
private var INSTANCE: AppSingleton? = null
// syncronized makes sure that all instances of the singleton are actually the only existing one
fun getInstance(context: Contecxt) = INSTANCE ?: syncronized(this) {
// synchronized makes sure that all instances of the singleton are actually the only existing one
fun getInstance(context: Context) = INSTANCE ?: synchronized(this) {
INSTANCE ?: Singleton(context).also {
INSTANCE = it
}
@ -75,10 +75,10 @@ override fun onCreate() {
Controller to handle data from the objects and interact with the Database
```kotlin
sqLiteDatabse = AppISngleton.getInstance().database // reference to the database from the singleton
sqLiteDatabase = AppISingleton.getInstance().database // reference to the database from the singleton
contentValues = ContentValues() // dict like structure to insert data in DB
contentValuest.put("DB_Column", value) // put data in the structure
contentValues.put("DB_Column", value) // put data in the structure
// insertion query V1
sqLiteDatabase?.insert("table", null, contentValue)

8
Android/activity.xml.md
View file

@ -4,7 +4,7 @@
### Colors, Style, Strings
These resorsces are located in `app/src/main/res/values/<resource_type>.xml`
These resources are located in `app/src/main/res/values/<resource_type>.xml`
`@color/colorName` -> access to *color definition* in `colors.xml`
`@string/stringName` -> access to *string definition* in `strings.xml` (useful for localization)
`@style/styleName` -> access to *style definition* in `styles.xml`
@ -65,7 +65,7 @@ A **View Group** or **Layout** is a container of Views.
```
`android:layout_width`, `android:layout_heigth`:
`android:layout_width`, `android:layout_height`:
* fixed value (dp, sp)
* match_parent
@ -141,7 +141,7 @@ Layout that arranges other views either horizontally in a single column or verti
```xml
<!--ID is necessary for identification -->
<View
android:id="@+id/uniquieId"
android:id="@+id/uniqueId"
android:layout_width="value"
android:layout_height="value"
/>
@ -164,7 +164,7 @@ The scroll view can only have one child. If the child is a layout than the layou
```xml
<ScrollView
android:id="@+id/uniquieId"
android:id="@+id/uniqueId"
android:layout_width="value"
android:layout_height="value">
<!-- single child -->

38
Bash/Bash Commands.md
View file

@ -4,20 +4,20 @@
## Basic Commands
### Elevated Priviledges and Users
### Elevated Privileges and Users
[sudo vs su](https://unix.stackexchange.com/questions/35338/su-vs-sudo-s-vs-sudo-i-vs-sudo-bash/35342)
```bash
sudo su # login as root (user must be sudoer, root password not required) DANGEROUS
sudo -s # act as root and inherit current user enviroment (env as is now, along current dir and env vars) SAFE (can modify user enviroment)
sudo -i # act as root and and use a clean enviroment (goes to user's home, runs .bashrc) SAFEST
sudo su # login as root (user must be sudoers, root password not required) DANGEROUS
sudo -s # act as root and inherit current user environment (env as is now, along current dir and env vars) SAFE (can modify user environment)
sudo -i # act as root and and use a clean environment (goes to user's home, runs .bashrc) SAFEST
sudo COMMAND # run a command w\ root permissions
sudo -u USER COMMAND # run command as user
su # become root (must know root password) DANGEROUS
su - USER # change user and load it's home folder
su USER # change user but dont load it's home folder
su USER # change user but don't load it's home folder
```
### Getting Info
@ -51,7 +51,7 @@ popd # return to previous directory (before pushd)
```sh
touch FILE # change FILE timestamp fi exists, create file otherwise
cat [FILE] # concatenate files and print on statndard output (FD 1)
cat [FILE] # concatenate files and print on standard output (FD 1)
cat >> FILE # append following content ot file (Ctrl+D to stop)
file FILE # discover file extension and format
stat FILE # display file or file system status
@ -60,7 +60,7 @@ tail # output the last part of a file
tail [-nNUM] # output the last NUM lines
more # filter for paging through text one screenful at a time
less # opposite of more (display big file in pages), navigate with arrow keys or spacebar
less # opposite of more (display big file in pages), navigate with arrow keys or space bar
cut # remove sections from each line of files
cut -[d --delimiter=DELIM] # use DELIM instead of TAB for field delimiter
@ -74,10 +74,10 @@ rmdir DIRECTORY # remove directory only if is empty
mkdir DIRECTORY # make directories
mv SOURCE DESTINATION # move or raneme files
mv SOURCE DESTINATION # move or rename files
mv SOURCE DIRECTORY # move FILE to DIRECTORY
cp SOURCE DESTINATION # copy SOURCE to DESTIANTION
cp SOURCE DESTINATION # copy SOURCE to DESTINATION
```
### Files Permissions & Ownership
@ -125,7 +125,7 @@ chgrp [OPTION]... GROUP FILE... # change group ownership
find [path] [expression] # search file in directory hierarchy
find [start-position] -type f -name FILENAME # search for a file named "filename"
find [start-position] -type d -name DIRNAME # search for a directory named "dirname"
find [path] -exec <command> {} \; # ececute command on found items (identified by {})
find [path] -exec <command> {} \; # execute command on found items (identified by {})
[ -f "path" ] # test if a file exists
[ -d "path" ] # test if a folder exists
@ -140,11 +140,11 @@ command | sudo tee FILE # operate on file w/o using shell as su
echo # display a line of text
echo "string" > FILE # write lin of text to file
echo "string" >> FILE # append line o ftext to end of file (EOF)
echo "string" >> FILE # append line of text to end of file (EOF)
wget URL # download repositories to linux machine
curl # dovnlaod the contents of a URL
curl # download the contents of a URL
curl [-I --head] # Fetch the headers only
ps [-ax] # display processes
@ -161,8 +161,8 @@ diff FILES # compare files line by line
shellcheck FILE # shell linter
xargs [COMMAND] # build and execute command lines from standard input
# xargs reads items form the standard input, delimites by blanks or newlines, and executes the COMMAND one or more times with the items as argumests
watch [OPTIONS] COMMAND # execute a program periodically, showing output fullscreen
# xargs reads items form the standard input, delimited by blanks or newlines, and executes the COMMAND one or more times with the items as arguments
watch [OPTIONS] COMMAND # execute a program periodically, showing output full-screen
watch -n SECONDS COMMAND # execute command every SECONDS seconds (no less than 0.1 seconds)
```
@ -172,10 +172,10 @@ watch -n SECONDS COMMAND # execute command every SECONDS seconds (no less than
```bash
sed # stream editor for filtering and transforming text
sed -E "s/REGEX/replacement/" # subsitute text ONCE (-E uses modern REGEX)
sed -E "s/REGEX/replacement/g" # subsitute text multiple times (every match)
sed -E "s/REGEX/replacement/" # substitute text ONCE (-E uses modern REGEX)
sed -E "s/REGEX/replacement/g" # substitute text multiple times (every match)
wc [FILE] # print newline, word and byte countd for each file
wc [FILE] # print newline, word and byte count for each file
wc [-m --chars] FILE # print character count
wc [-c --bytes] FILE # print bytes count
wc [-l --lines] FILE # print lines count
@ -185,8 +185,8 @@ sort [FILE] # sort lines of a text file
uniq [INPUT [OUTPUT]] # report or omit repeated lines (from INPUT to OUTPUT)
uniq [-c --count] # prefix lines w/ number of occurrences
uniq [-d --repeated] # plrint only duplicare lines, one for each group
uniq [-D] # plrint only duplicare lines
uniq [-d --repeated] # print only duplicare lines, one for each group
uniq [-D] # print only duplicare lines
paste [FILE] # merge lines of files
paste [-d --delimiters=LIST] # use delimiters from LIST

32
Bash/Bash Scripting.md
View file

@ -10,7 +10,7 @@
Interactive mode --> shell waits for user's commands
Non-interactive mode --> shell runs scripts
## File & Directories Permissons
## File & Directories Permissions
File:
@ -35,12 +35,12 @@ Bash gets commands by reading lines.
As soon as it's read enough lines to compose a complete command, bash begins running that command.
Usually, commands are just a single line long. An interactive bash session reads lines from you at the prompt.
Non-interactive bash processes read their commands from a file or stream.
Files with a hashbang as their first line (and the executable permission) can be started by your system's kernel like any other program.
Files with a shebang as their first line (and the executable permission) can be started by your system's kernel like any other program.
### First Line Of Bash
`#!/bin/env bash`
Hashbang indicating whitch interpreter to use
shebang indicating which interpreter to use
### Simple Command
@ -73,7 +73,7 @@ command_1 || command_2 || ... # execute successive commands only if preceding o
{command_1; command_2; ...} # sequence of commands executed as one
```
### Functions (blocks of easely reusable code)
### Functions (blocks of easily reusable code)
`function_name () {compound_command}`
Bash does not accept func arguments, parentheses must be empty
@ -125,7 +125,7 @@ x>&-, x<&- # close FD x (stream disconnected from FD x)
`*` matches any kind of text (even no text).
`?` matches any single character.
`[characters]` mathces any single character in the given set.
`[characters]` matches any single character in the given set.
`[[:classname:]]` specify class of characters to match.
`{}` expand list of arguments (applies command to each one)
@ -137,7 +137,7 @@ x>&-, x<&- # close FD x (stream disconnected from FD x)
`@(pattern [| pattern ...])` matches when any of the patterns in the list appears just once. ("one of ...").
`!(pattern [| pattern ...])` matches only when none of the patterns in the list appear. ("none of ...").
## Command Substituition
## Command Substitution
With Command Substitution, we effectively write a command within a command, and we ask bash to expand the inner command into its output and use that output as argument data for the main command.
@ -148,9 +148,9 @@ $(inner_command) # $ --> value-expansion prefix
## Shell Variables
```bash
varname=value # variable assignement
varname="$(command)" # command sobstituition, MUST be double-quoted
"$varname", "${varname}" # variable expansion, MUST be double-quoted (name substituited w/ varaible content)
varname=value # variable assignment
varname="$(command)" # command substitution, MUST be double-quoted
"$varname", "${varname}" # variable expansion, MUST be double-quoted (name substituted w/ variable content)
$$ # pid
$# # number of arguments passed
@ -158,7 +158,7 @@ $@ # all arguments passed
${n} # n-th argument passed to the command
$0 # name of the script
$_ # last argument passed to the command
$? # error message of the last (previous) comman
$? # error message of the last (previous) command
!! # executes last command used (echo !! prints the last command)
```
@ -173,7 +173,7 @@ $? # error message of the last (previous) comman
`${parameter/#pattern/replacement}` replaces the string that matches the pattern at the beginning of the value with the replacement.
`${parameter/%pattern/replacement}` replaces the string that matches the pattern at the end of the value with the replacement.
`${#parameter}` expands the length of the value (in bytes).
`${parametr:start[:length]}` expands a part of the value, starting at start, length bytes long.
`${parameter:start[:length]}` expands a part of the value, starting at start, length bytes long.
Counts from the end rather than the beginning by using a (space followed by a) negative value.
`${parameter[^|^^|,|,,][pattern]}` expands the transformed value, either upper-casing or lower-casing the first or all characters that match the pattern.
Omit the pattern to match any character.
@ -195,7 +195,7 @@ fi
### Test Command
`[[ arggument_1 <operator> argument_2 ]]`
`[[ argument_1 <operator> argument_2 ]]`
### Arithmetic expansion and evaluation
@ -212,7 +212,7 @@ fi
[[ "$a" -le "$b" ]] # less than or equal to
```
### Arithmetic Comperison Operators
### Arithmetic Comparison Operators
```bash
(("$a" > "$b")) # greater than
@ -221,10 +221,10 @@ fi
(("$a" <= "$b")) # less than or equal to
```
### String Compatison Operators
### String Comparison Operators
```bash
[ "$a" = "$b" ] # is equal to (whitespace atoun operator)
[ "$a" = "$b" ] # is equal to (whitespace around operator)
[[ $a == z* ]] # True if $a starts with an "z" (pattern matching)
[[ $a == "z*" ]] # True if $a is equal to z* (literal matching)
@ -244,7 +244,7 @@ fi
```bash
command_1 || command_2 # if command_1 fails executes command_2
command_1 && command_2 # executes command_2 only if command_1 succedes
command_1 && command_2 # executes command_2 only if command_1 succeeds
```
## Loops

96
C++/C++.md
View file

@ -34,12 +34,12 @@ const type constant_name = value;
```cpp
#include <cstdlib>
system("pause");
getchar(); // waits imput from keyboard, if is last instruction will prevent closing console until satisfied
getchar(); // waits input from keyboard, if is last instruction will prevent closing console until satisfied
```
### Namespace definition
Can be omitted and replaced by namespce`::`
Can be omitted and replaced by namespace`::`
`using namespace <namespace>;`
### Main Function
@ -72,7 +72,7 @@ Type | Value Range | Byte
`short` | -32768 to 32765 | 1
`unsigned short` | 0 to 65535 | 1
`int` | -2147483648 to 2147483647 | 4
`unisgned int` | 0 to 4294967295 | 4
`unsigned int` | 0 to 4294967295 | 4
`long` | -2147483648 to 2147483647 | 4
`unsigned long` | 0 to 4294967295 | 4
`long long` | | 8
@ -105,7 +105,7 @@ Example | Type
Example | Type
------------|-------------
`3.14159L` | long double
`60.22e23f` | flaot
`60.22e23f` | float
Code | Value
----------|---------------
@ -123,7 +123,7 @@ Code | Value
Escape Character | Character
-------------------|-----------------------------
`\n` | neweline
`\n` | newline
`\r` | carriage return
`\t` | tab
`\v` | vertical tab
@ -140,7 +140,7 @@ Escape Character | Character
```cpp
cout << expression; // print line on screen (no automatic newline)
cout << expressin_1 << expreeeion_2; // concatenation of outputs
cout << expression_1 << expression_2; // concatenation of outputs
cout << expression << "\n"; // print line on screen
cout << expression << endl; // print line on screen
@ -153,19 +153,19 @@ printf_s("text %<fmt_spec>", variable);
### Input
```cpp
#iclude <iostream>
#include <iostream>
cin >> var; //space terminates value
cin >> var_1 >> var_2;
//if used after cin >> MUST clear buffer with cin.ignore(), cin.sync() or std::ws
getline(stream, string, delimiter) //read input from stream (usially CIN) and store in in string, a different delimiter character can be set.
getline(stream, string, delimiter) //read input from stream (usually CIN) and store in in string, a different delimiter character can be set.
#include <stdio.h>
scanf("%<fmt_spec>", &variable); // has problems, use SCANF_S
scanf_s("%<fmt_spec>", &variable); //return number of succescully accepted inputs
scanf_s("%<fmt_spec>", &variable); //return number of successfully accepted inputs
```
### Fromat Specifiers %[width].[lenght][specifier]
### Format Specifiers %[width].[length][specifier]
Specifier | Specified Format
------------|-----------------------------------------
@ -210,9 +210,9 @@ if (!(cin >> var)) // if cin fails to get an input
#include <iomanip>
cout << stew(print_size) << setprecision(num_digits) << var; //usage
setbase(base) //set numberica base [dec, hex, oct]
setbase(base) //set numeric base [dec, hex, oct]
setw(print_size) //set the total number of characters to display
setprecision(num_digits) //sets the number of decimal digits to siaplay
setprecision(num_digits) //sets the number of decimal digits to display
setfill(character) //use character to fill space between words
```
@ -263,7 +263,7 @@ a `^` b, a `xor` b, | bitwise **XOR**
a `<<` b | bitwise left shift
a `>>` b | bitwise right shift
### Compound Assignement O
### Compound Assignment O
Operator | Operation
------------|------------
@ -297,7 +297,7 @@ abs(x); // absolute value
labs(x); //absolute value if x is long, result is long
fabs(x); //absolute value if x i float, result is float
sqrt(x); // square root
ceil(x); // ceil function (next initeger)
ceil(x); // ceil function (next integer)
floor(x); // floor function (integer part of x)
log(x); // natural log of x
log10(x); // log base 10 of x
@ -337,7 +337,7 @@ isxdigit(c); //true if c is HEX DIGIT
```cpp
#include <ctype.n>
tolower(c); //transfromas charatcer in lowercase
tolower(c); //transforms character in lowercase
toupper(c); //transform character in uppercase
```
@ -346,7 +346,7 @@ toupper(c); //transform character in uppercase
```cpp
#include <time>
#include <stdlib.h>
srand(time(NULL)); //initzialize seed
srand(time(NULL)); //initialize seed
var = rand() //random number
var = (rand() % max + 1) //random numbers between 0 & max
var = (rand() % (max - min + 1)) + min //random numbers between min & max
@ -367,7 +367,7 @@ fflush(FILE); // empty output buffer end write its content on argument passed
#include <string>
string string_name = "string_content"; //string declaration
string string_name = string("strintg_content"); // string creation w/ constructor
string string_name = string("string_content"); // string creation w/ constructor
string.length //returns the length of the string
@ -383,9 +383,9 @@ string[pos] //returns char at index pos
### String Functions
```cpp
string.c_str() //transfroms the string in pointer to char[] (char array aka C string) ter,iomated by '\0'
string.c_str() //transforms the string in pointer to char[] (char array aka C string) terminated by '\0'
strlen(string); //return lenght (num of chars) of the string
strlen(string); //return length (num of chars) of the string
strcat(destination, source); //appends chars of string2 to string1
strncat(string1, string2, nchar); //appends the first n chars of string 2 to string1
strcpy(string1, string2.c_str()); //copies string2 into string1 char by char
@ -394,7 +394,7 @@ strcmp(string1, string2); //compares string1 w/ string2
strncmp(string1, string2, n); //compares first n chars
//returns < 0 if string1 precedes string2
//returns 0 if string1 == string2
// returns > 0 if string1 succedes string2
// returns > 0 if string1 succeeds string2
strchr(string, c); //returns index of c in string if it exists, NULL otherwise
strstr(string1, string2); //returns pointer to starting index of string1 in string2
strpbrk(string, charSet); //Returns a pointer to the first occurrence of any character from strCharSet in str, or a NULL pointer if the two string arguments have no characters in common.
@ -430,7 +430,7 @@ vector<type> vector_name = {values}; //variable length array
```cpp
if (condition)
//single istruction
//single instruction
if (condition) {
@ -448,7 +448,7 @@ if (condition) {
}
```
## IF-ELSE mutli-branch
## IF-ELSE multi-branch
```cpp
if (condition) {
@ -532,7 +532,7 @@ To return multiple variables those variables can be passed by reference so that
### Standard Function
```cpp
type functionName (parameters) { //parametri formali aka arguents
type functionName (parameters) { //parametri formali aka arguments
//code here
return <expression>;
}
@ -548,7 +548,7 @@ void functionName (parameters) {
### Arguments passed by reference without pointers
Passing arguments by reference causes modifications made inside the funtion to be propagated to the values outside.
Passing arguments by reference causes modifications made inside the function to be propagated to the values outside.
Passing arguments by values copies the values to the arguments: changes remain inside the function.
```cpp
@ -562,7 +562,7 @@ type functionName (type &argument1, ...) {
### Arguments passed by reference with pointers
Passing arguments by reference causes modifications made inside the funtion to be propagated to the values outside.
Passing arguments by reference causes modifications made inside the function to be propagated to the values outside.
Passing arguments by values copies the values to the arguments: changes remain inside the function.
```cpp
@ -578,22 +578,22 @@ type function_name (type *argument_1, ...) {
```cpp
type arrayName[dimension]; //array declaration
type arrayName[dimension] = {value1, value2, ...}; //array declaration & inizialization, values number must match dimension
type arrayName[dimension] = {value1, value2, ...}; //array declaration & initialization, values number must match dimension
array[index] //item access, index starts at 0 (zero)
array[index] = value; //value assignement at position index
array[index] = value; //value assignment at position index
```
## String as array of Chars
```cpp
char string[] = "text"; //converts string in char array, string length determines dimesion of the array
char string[] = "text"; //converts string in char array, string length determines dimension of the array
string str = string[] //a array of chars is automatically converted to a string
```
## Array as function parameter
The dimesion is not specified because it is determined by the passed array.
The dimension is not specified because it is determined by the passed array.
The array is passed by reference.
```cpp
@ -601,7 +601,7 @@ type function(type array[]){
//code here
}
//array is not modificable inside the function (READ ONLY)
//array is not modifiable inside the function (READ ONLY)
type function(const type array[]){
//code here
}
@ -624,8 +624,8 @@ type function(type matrix[][columns]){
//code here
};
//martix values READ ONLY
type function(const type matric[][columns]){
//matrix values READ ONLY
type function(const type matrix[][columns]){
//code here
}
@ -636,7 +636,7 @@ type function(type matrix[][dim2]...[dimN]){
## Record (struct)
List of non omogeneous items
List of non homogeneous items
### Struct Definition (before functions, outside main)
@ -654,10 +654,10 @@ variable.field //field access
## Pointers
Pointers hold memory adresses of declared variables, they should be initialized to NULL.
Pointers hold memory addresses of declared variables, they should be initialized to NULL.
```cpp
type *pointer = &variable; //pointer init and assignement
type *pointer = &variable; //pointer init and assignment
type *pointer = NULL;
type *pointer = otherPointer;
type **pointerToPointer = &pointer; // pointerToPointer -> pointer -> variable
@ -668,7 +668,7 @@ pointer type and variable type **must** match.
(*) --> "value pointed to by"
```cpp
pointer //addres of pointed value (value of variable)
pointer //address of pointed value (value of variable)
*pointer //value of pointed variable
**pointer //value pointed by *pointer (pointer to pointer)
```
@ -690,15 +690,15 @@ pointer++; //change pointed value to successive "cell" of array
func(array) //pass entire array to function (no need to use (&) to extract address)
type func(type* array){
array[index] //acces to item of array at index
array[index] //access to item of array at index
}
```
### Pointer to Struct
```cpp
(*structPointer).field //acces to field value
structPointer->structField //acces to field value
(*structPointer).field //access to field value
structPointer->structField //access to field value
```
## Dynamic Structures
@ -711,7 +711,7 @@ Every node is composed by two parts:
* the value (item)
* pointer to successive node
**Lists** are *linear* dinamyc structures in which is only defined the preceding and succeding item. A List is a group of homogeneous items (all of the same type).
**Lists** are *linear* dynamic structures in which is only defined the preceding and succeeding item. A List is a group of homogeneous items (all of the same type).
**Trees**, **Graphs** are non *linear* dynamic structures in which an item cha have multiple successors.
@ -728,7 +728,7 @@ struct Node {
}
```
#### Node Instertion
#### Node Insertion
```cpp
Node *stackNode; //current node
@ -740,7 +740,7 @@ int nodeValue;
stackNode = new Node; //create new node
stackNode->value = nodevalue; //valorize node
stackNode->next = head; //update node poiter to old head adding it to the stack
stackNode->next = head; //update node pointer to old head adding it to the stack
head = stackNode; //update head to point to new first node
```
@ -783,12 +783,12 @@ Thus the first and last node will have a component empty since they only point t
### Dynamic Memory Allocation
C/C++ does not automatically free allocated memory when nodes are deleted. It must be done manuallty.
C/C++ does not automatically free allocated memory when nodes are deleted. It must be done manually.
In **C++**:
* `new` is used to allocate memory dynamically.
* `delete` is use to free the dinamically allocated memory.
* `delete` is use to free the dynamically allocated memory.
In **C**:
@ -807,7 +807,7 @@ free(pointer) //freeing of memory
The object oriented approach is based on the use of *streams*.
A **Stream** can be considered a stream of data that passes sequentially from a source to a destination.
The avaiable classes in C++ to operate on files are:
The available classes in C++ to operate on files are:
* `ifstream` for the input (reading)
* `ofstream` for the output (writing)
@ -822,7 +822,7 @@ ifstream file;
file.open("filename"); //read from file
ofstream file;
file.open("filename"); //writo to file
file.open("filename"); //write to file
fstream file;
@ -836,7 +836,7 @@ file.open("filename", ios::binary); //opens file in binary format
```
If file opening fails the stream has value 0, otherwise the value is the assigned memory address.
Opening modes can be conbined with the OR operator: `ios::mode | ios::mode`.
Opening modes can be combined with the OR operator: `ios::mode | ios::mode`.
### File Reading & Writing
@ -858,5 +858,5 @@ do {
Once a stream is in a **state of error** it will remain so until the status flags are *explicitly resetted*. The input operations on such a stream are *void* until the reset happens.
To clear the status of a stream the `clear()` method is used.
Furthermore, when an error on the stream happens **the stream is not cleared** of it's charaters contents.
Furthermore, when an error on the stream happens **the stream is not cleared** of it's characters contents.
To clear the stream contents the `ignore()` method is used.

46
Database/MongoDB.md
View file

@ -2,7 +2,7 @@
The database is a container of **collections**. The collections are containers of **documents**.
The documents are _schema-less_ that is they have a dynamic structure that can change between documents in the same colletion.
The documents are _schema-less_ that is they have a dynamic structure that can change between documents in the same collection.
## Data Types
@ -17,7 +17,7 @@ The documents are _schema-less_ that is they have a dynamic structure that can c
| Embedded Document | `{"a": {...}}` |
| Embedded Array | `{"b": [...]}` |
It's mandatory for each document ot have an uniwue field `_id`.
It's mandatory for each document ot have an unique field `_id`.
MongoDB automatically creates an `ObjectId()` if it's not provided.
## Databases & Collections Usage
@ -69,7 +69,7 @@ db.<collection>.insertOne({document}) # implicit collection creation
`$<key>` is used to access the value of the field dynamically
```json
{ "$expr": { <expression> } } // aggregetion expresion, variables, conditional expressions
{ "$expr": { <expression> } } // aggregation expression, variables, conditional expressions
{ "$expr": { "$comparison_operator": [ "$<key>", "$<key>" ] } } // compare field values
```
@ -80,13 +80,13 @@ db.<collection>.insertOne({document}) # implicit collection creation
It's possible to insert a single document with the command `insertOne()` or multiple documents with `insertMany()`.
Isertion results:
Insertion results:
- error -> rollback
- success -> entire documents gets saved
```sh
# explicit collection creation, all options are otional
# explicit collection creation, all options are optional
db.createCollection( <name>,
{
capped: <boolean>,
@ -121,7 +121,7 @@ db.<collection>.insertMany([ { document }, { document } ] , { "ordered": false }
```sh
db.<collection>.findOne() # find only one document
db.<collection>.find(filter) # show selected documents
db.<collection>.find(filter, {"<key>": 1}) # show selected values form documents (1 or true => show, 0 or false => dont show, cant mix 0 and 1)
db.<collection>.find(filter, {"<key>": 1}) # show selected values form documents (1 or true => show, 0 or false => don't show, cant mix 0 and 1)
db.<collection>.find(filter, {_id: 0, "<key>": 1}) # only _id can be set to 0 with other keys at 1
db.<collection>.find().pretty() # show documents formatted
db.<collection>.find().limit(n) # show n documents
@ -155,7 +155,7 @@ db.<collection>.find().hint( { $natural : -1 } ) # force the query to perform a
```sh
db.<collection>.updateOne(filter, $set: {"<key>": value}) # add or modify values
db.<collection>.updateOne(filter, $set: {"<key>": value}, {upsert: true}) # add or modify values, if attribute doesent exists create it
db.<collection>.updateOne(filter, $set: {"<key>": value}, {upsert: true}) # add or modify values, if attribute doesn't exists create it
db.<collection>.updateMany(filter, update)
@ -175,7 +175,7 @@ db.dropDatabase() # delete entire database
## [Mongoimport](https://docs.mongodb.com/database-tools/mongoimport/)
Utility to import all docs into a specified collection.
If the collection alredy exists `--drop` deletes it before reuploading it.
If the collection already exists `--drop` deletes it before reuploading it.
**WARNING**: CSV separators must be commas (`,`)
```sh
@ -228,17 +228,17 @@ mongoexport --collection=<collection> <options> <connection-string>
**Nested / Embedded Documents**:
- Group data locically
- Group data logically
- Optimal for data belonging together that do not overlap
- Should avoid nesting too deep or making too long arrays (max doc size 16 mb)
```json
{
_id: Objectid()
"_id": Objectid()
"<key>": "value"
"<key>": "value"
innerDocument: {
"innerDocument": {
"<key>": "value"
"<key>": "value"
}
@ -249,19 +249,19 @@ mongoexport --collection=<collection> <options> <connection-string>
- Divide data between collections
- Optimal for related but shared data used in relations or stand-alone
- Allows to overtake nidification and size limits
- Allows to overtake nesting and size limits
NoSQL databases do not have relations and references. It's the app that has to handle them.
```json
{
"<key>": "value"
references: ["id1", "id2"]
"references": ["id1", "id2"]
}
// referenced
{
_id: "id1"
"_id": "id1"
"<key>": "value"
}
```
@ -273,7 +273,7 @@ Indexes support the efficient execution of queries in MongoDB.
Without indexes, MongoDB must perform a _collection scan_ (_COLLSCAN_): scan every document in a collection, to select those documents that match the query statement.
If an appropriate index exists for a query, MongoDB can use the index to limit the number of documents it must inspect (_IXSCAN_).
Indexes are special data structures that store a small portion of the collection’s data set in an easy to traverse form. The index stores the value of a specific field or set of fields, ordered by the value of the field. The ordering of the index entries supports efficient equality matches and range-based query operations. In addition, MongoDB can return sorted results by using the ordering in the index.
Indexes are special data structures that store a small portion of the collection's data set in an easy to traverse form. The index stores the value of a specific field or set of fields, ordered by the value of the field. The ordering of the index entries supports efficient equality matches and range-based query operations. In addition, MongoDB can return sorted results by using the ordering in the index.
Indexes _slow down writing operations_ since the index must be updated at every writing.
@ -283,13 +283,13 @@ Indexes _slow down writing operations_ since the index must be updated at every
- **Normal**: Fields sorted by name
- **Compound**: Multiple Fields sorted by name
- **Multykey**: values of sorted arrays
- **Multikey**: values of sorted arrays
- **Text**: Ordered text fragments
- **Geospatial**: ordered geodata
**Sparse** indexes only contain entries for documents that have the indexed field, even if the index field contains a null value. The index skips over any document that is missing the indexed field.
### Diagnosys and query planning
### Diagnosis and query planning
```sh
db.<collection>.find({...}).explain() # explain won't accept other functions
@ -345,9 +345,9 @@ Profiling Levels:
Logs are saved in the `system.profile` _capped_ collection.
```sh
db.setProgilingLevel(n) # set profiler level
db.setProfilingLevel(n) # set profiler level
db.setProfilingLevel(1, { slowms: <ms> })
db.getProfilingStatus() # check profiler satus
db.getProfilingStatus() # check profiler status
db.system.profile.find().limit(n).sort( {} ).pretty() # see logs
db.system.profile.find().limit(n).sort( { ts : -1 } ).pretty() # sort by decreasing timestamp
@ -358,7 +358,7 @@ db.system.profile.find().limit(n).sort( { ts : -1 } ).pretty() # sort by decrea
**Authentication**: identifies valid users
**Authorization**: identifies what a user can do
- **userAdminAnyDatabase**: can admin every db in the istance (role must be created on admin db)
- **userAdminAnyDatabase**: can admin every db in the instance (role must be created on admin db)
- **userAdmin**: can admin the specific db in which is created
- **readWrite**: can read and write in the specific db in which is created
- **read**: can read the specific db in which is created
@ -391,7 +391,7 @@ db.createUser(
## Sharding
**Sharding** is a MongoDB concept through which big datasests are subdivided in smaller sets and distribuited towards multiple instances of MongoDB.
**Sharding** is a MongoDB concept through which big datasets are subdivided in smaller sets and distributed towards multiple instances of MongoDB.
It's a technique used to improve the performances of large queries towards large quantities of data that require al lot of resources from the server.
A collection containing several documents is splitted in more smaller collections (_shards_)
@ -400,7 +400,7 @@ Shards are implemented via cluster that are none other a group of MongoDB instan
Shard components are:
- Shards (min 2), instances of MongoDB that contain a subset of the data
- A config server, instasnce of MongoDB which contains metadata on the cluster, that is the set of instances that have the shard data.
- A config server, instance of MongoDB which contains metadata on the cluster, that is the set of instances that have the shard data.
- A router (or `mongos`), instance of MongoDB used to redirect the user instructions from the client to the correct server.
![Shared Cluster](../.images/mongodb_shared-cluster.png "Components of a shared cluster")
@ -413,7 +413,7 @@ A **replica set** in MongoDB is a group of `mongod` processes that maintain the
Sequence of operations applied to a collection as a _pipeline_ to get a result: `db.collection.aggregate(pipeline, options)`.
[Aggragations Stages][aggeregation_stages_docs]:
[Aggregations Stages][aggeregation_stages_docs]:
- `$lookup`: Right Join
- `$match`: Where

6
Database/Redis.md
View file

@ -45,7 +45,7 @@ RPUSH <key> <value1> <value2> ... # add one or more values to the end of the lis
LPUSH <key> <value1> <value2> ... # add one or more values to the start of a list
LLEN # number of items in the list
LRANGE <key> <start_index> <end_index> # return a subset of the list, end index included. Negative indexes caout backwards from the end
LRANGE <key> <start_index> <end_index> # return a subset of the list, end index included. Negative indexes count backwards from the end
LPOP # remove and return the first item fro the list
RPOP # remove and return the last item fro the list
@ -56,7 +56,7 @@ RPOP # remove and return the last item fro the list
A set is similar to a list, except it does not have a specific order and each element may only appear once.
```sh
SADD <key> <value1> <value2> ... # add one or more values to the set (retunr 0 if values are alredy inside)
SADD <key> <value1> <value2> ... # add one or more values to the set (return 0 if values are already inside)
SREM <key> <value> # remove the given member from the set, return 1 or 0 to signal if the member was actually there or not.
SPOP <key> <value> # remove and return value from the set
@ -97,7 +97,7 @@ HGET <key> <field> # get data on a single field
HKEYS <key> # get all the fields in a hash
HVALS <key> # get all the values in a hash
HDEL <key> <field_1> <field_2> ... # delete one or more field hases
HDEL <key> <field_1> <field_2> ... # delete one or more field hashes
HMGET <key> <field> [<field> ...] # get the values of all the given hash fields
HMSET <key> <field> <value> [<field> <value> ...] # set multiple hash fields to multiple values

61
Database/SQL.md
View file

@ -6,7 +6,7 @@
```sql
show databases; -- mostra database
CREATE DATABASE <database>; -- dataabse creation
CREATE DATABASE <database>; -- database creation
use <database_name>; -- usa un database particolare
exit; -- exit mysql
@ -67,7 +67,7 @@ ALTER TABLE <table>
```sql
INSERT INTO <table> (field_1, ...) VALUES (value_1, ...), (value_1, ...);
INSERT INTO <table> VALUES (value_1, ...), (value_1, ...); -- field order MUST respest tables's columns order
INSERT INTO <table> VALUES (value_1, ...), (value_1, ...); -- field order MUST respect tables's columns order
```
### Data Update
@ -93,36 +93,36 @@ SHOW columns FROM <table>; -- show table columns
DESCRIBE <table>; -- shows table
```
### Alias Tabelle
### Alias
```sql
SELECT <field/funzione> as <alias>; -- mostra <field/funzione> con nome <alias>
SELECT <field> as <alias>; -- shows <field/funzione> with name <alias>
```
### Selezione Condizionale
### Conditional Selection
```sql
SELECT * FROM <table> WHERE <condition>; -- mostra elementi che rispettano la condizione
AND, OR, NOT -- connettivi logici
SELECT * FROM <table> WHERE <condition>; -- shows elements that satisfy the condition
AND, OR, NOT -- logic connectors
SELECT * FROM <table> WHERE <field> Between <value_1> AND <value_2>;
```
### Ordinamento
### Ordering
```sql
SELECT * FROM <table> ORDER BY <field>, ...; -- mostra tabella ordinata in base a colonna <field>
SELECT * FROM <table> ORDER BY <field>, ... DESC; -- mostra tabella ordinata decrescente in base a colonna <field>
SELECT * FROM <table> ORDER BY <field>, ... LIMIT n; -- mostra tabella ordinata in base a colonna <field>, mostra n elementi
SELECT * FROM <table> ORDER BY <field>, ...; -- shows the table ordered by <field>
SELECT * FROM <table> ORDER BY <field>, ... DESC; -- shows the table ordered by <field>, decreasing order
SELECT * FROM <table> ORDER BY <field>, ... LIMIT n; -- shows the table ordered by <field>, shows n items
SELECT TOP(n) * FROM <table> ORDER BY <field>, ...; -- T-SQL
```
## Raggruppamento
## Grouping
```sql
SELECT * FROM <table> GROUP BY <field>;
SELECT * FROM <table> GROUP BY <field> HAVING <condition>;
SELECT DISTINCT <field> FROM <table>; -- mostra elementi senza riperizioni
SELECT DISTINCT <field> FROM <table>; -- shows elements without repetitions
```
### Ricerca caratteri in valori
@ -130,10 +130,10 @@ SELECT DISTINCT <field> FROM <table>; -- mostra elementi senza riperizioni
`%` 0+ caratteri
```sql
SELECT * FROM <table> WHERE <field> LIKE '<char>%'; -- seleziona elemnti in <field> inizianti per <char>
SELECT * FROM <table> WHERE <field> LIKE '%<char>'; -- seleziona elemnti in <field> terminanti per <char>
SELECT * FROM <table> WHERE <field> LIKE '%<char>%'; -- seleziona elemnti in <field> contenenti <char>
SELECT * FROM <table> WHERE <field> NOT LIKE '%<char>%'; -- seleziona elemnti in <field> non contenenti <char>
SELECT * FROM <table> WHERE <field> LIKE '<char>%'; -- selects items in <field> that start with <char>
SELECT * FROM <table> WHERE <field> LIKE '%<char>'; -- selects items in <field> that end with <char>
SELECT * FROM <table> WHERE <field> LIKE '%<char>%'; -- selects items in <field> that contain <char>
SELECT * FROM <table> WHERE <field> NOT LIKE '%<char>%'; -- selects items in <field> that do not contain <char>
```
### Selection from multiple tables
@ -143,18 +143,18 @@ SELECT a.<field>, b.<field> FROM <table> AS a, <table> AS b
WHERE a.<field> ...;
```
## Funzioni
## Functions
```sql
SELECT COUNT(*) FROM <field>; -- conta numero elemneti nel campo
SELECT MIN(*) FROM <table>; -- restituisce il valore minimo
SELECT MAX(*) FROM <table>; -- restituisce valore massimo
SELECT AVG(*) FROM <table>; -- media valori del campo
SELECT COUNT(*) FROM <field>; -- count of items in <field>
SELECT MIN(*) FROM <table>; -- min value
SELECT MAX(*) FROM <table>; -- max value
SELECT AVG(*) FROM <table>; -- mean of values
ALL (SELECT ...)
ANY (SELECT ...)
```
## Query Annidate
## Nested Queries
```sql
SELECT * FROM <table> WHERE EXISTS (SELECT * FROM <table>) -- selected field existing in subquery
@ -181,13 +181,10 @@ INSERT INTO <table>
## Join
Permette di legare due tabelle correlando i dati, le tabelle devono avere almeno un campo in comune.
Primary key deve comparire in altra tabella come foreign key.
```sql
SELECT * FROM <table1> JOIN <table2> ON <table1>.<field> = <table2>.<field>; -- seleziono tutti gli elementi che hanno una relarione tra le due tabelle
SELECT * FROM <table1> LEFT JOIN <table2> ON <condition>; -- seleziona tutti gli elementi di table1 e i eventuali elementi richiamati dal join
SELECT * FROM <table1> RIGHT JOIN <tabl2> ON <condition> -- -- seleziona tutti gli elementi di table2 e i eventuali elementi richiamati dal join
SELECT * FROM <table1> JOIN <table2> ON <table1>.<field> = <table2>.<field>;
SELECT * FROM <table1> LEFT JOIN <table2> ON <condition>;
SELECT * FROM <table1> RIGHT JOIN <table2> ON <condition>
```
[Inner Join, Left Join, Right Join, Full Outer Join](https://www.diffen.com/difference/Inner_Join_vs_Outer_Join)
@ -202,7 +199,7 @@ JOIN <table3> ON <table2>.<field> = <table3>.<field>;
[char, nchar, varchar, nvarchar](https://stackoverflow.com/questions/176514/what-is-the-difference-between-char-nchar-varchar-and-nvarchar-in-sql-server)
***
---
## T-SQL (MSSQL Server)
@ -230,7 +227,7 @@ DECLARE @var_name <type>
SET @var_name = <value>
-- use in query (memorize data)
SELECT @var_name = COUNT(*) -- query won't show results in the "table view" sice param is used in SELECT
SELECT @var_name = COUNT(*) -- query won't show results in the "table view" since param is used in SELECT
FROM <table> ...
-- display message (query won't show results in the "table view")
@ -263,7 +260,7 @@ CREATE PROCEDURE <Procedure_Name>
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from interfering with SELECT statements.
SET NOCOUNT ON; -- dont return number of selected rows
SET NOCOUNT ON; -- don't return number of selected rows
-- Insert statements for procedure here
SELECT ...

4
DotNet/ASP.NET/App Configuration.md
View file

@ -73,7 +73,7 @@ namespace App
// or
services.AddControllers(); // controllers w/o views
//or
sevices.AddControllersWithViews(); // MVC Controllers
services.AddControllersWithViews(); // MVC Controllers
//or
services.AddServerSideBlazor(); // needs Razor Pages
@ -147,7 +147,7 @@ Connection Strings & Secrets.
## `launchsettings.json`
Launch Settings & Deployement Settings.
Launch Settings & Deployment Settings.
```json
{

8
DotNet/ASP.NET/Blazor.md
View file

@ -16,7 +16,7 @@ The component class is usually written in the form of a Razor markup page with a
## Project Structure & Important Files
### Blazor Server Project Stucture
### Blazor Server Project Structure
```txt
Project
@ -45,7 +45,7 @@ Project
|- App.razor --> component root of the app
|
|- appsettings.json --> application settings
|- Program.cs --> App entrypoint
|- Program.cs --> App entry-point
|- Startup.cs --> services and middleware configs
```
@ -78,7 +78,7 @@ Project
|- App.razor --> component root of the app
|
|- appsettings.json --> application settings
|- Program.cs --> App entrypoint
|- Program.cs --> App entry-point
```
### Blazor PWA Project Structure
@ -148,7 +148,7 @@ Project
```cs
<Router AppAssembly="@typeof(Program).Assembly" PreferExactMatches="@true">
<Found Context="routeData"> // for component routing
<Found Context="routeData">
<RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
</Found>
<NotFound>

34
DotNet/ASP.NET/Filters.md
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@ -1,6 +1,6 @@
# [Filters](https://docs.microsoft.com/en-us/aspnet/core/mvc/controllers/filters)
**Filters** in ASP.NET Core allow code to be run *before* or *after* specific stages in the request processing pipeline.
**Filters** in ASP.NET Core allow code to be run _before_ or _after_ specific stages in the request processing pipeline.
Built-in filters handle tasks such as:
@ -11,7 +11,7 @@ Custom filters can be created to handle cross-cutting concerns. Examples of cros
## **How filters work**
Filters run within the *ASP.NET Core action invocation pipeline*, sometimes referred to as the *filter pipeline*. The filter pipeline runs after ASP.NET Core selects the action to execute.
Filters run within the _ASP.NET Core action invocation pipeline_, sometimes referred to as the _filter pipeline_. The filter pipeline runs after ASP.NET Core selects the action to execute.
![filter-pipeline-1](../../.images/dotnet_filter-pipeline-1.png)
![filter-pipeline-2](../../.images/dotnet_filter-pipeline-2.png)
@ -20,18 +20,18 @@ Filters run within the *ASP.NET Core action invocation pipeline*, sometimes ref
Each filter type is executed at a different stage in the filter pipeline:
- **Authorization filters** run first and are used to determine whether the user is authorized for the request. Authorization filters short-circuit the pipeline if the request is not authorized.
- **Authorization filters** run first and are used to determine whether the user is authorized for the request. Authorization filters short-circuit the pipeline if the request is not authorized.
- **Resource filters**:
- Run after authorization.
- `OnResourceExecuting` runs code before the rest of the filter pipeline. For example, `OnResourceExecuting` runs code before model binding.
- `OnResourceExecuting` runs code before the rest of the filter pipeline. For example, `OnResourceExecuting` runs code before model binding.
- `OnResourceExecuted` runs code after the rest of the pipeline has completed.
- **Action filters**:
- Run code immediately before and after an action method is called.
- Can change the arguments passed into an action.
- Can change the result returned from the action.
- Are **not** supported in Razor Pages.
- **Exception filters** apply global policies to unhandled exceptions that occur before the response body has been written to.
- **Result filters** run code immediately before and after the execution of action results. They run only when the action method has executed successfully. They are useful for logic that must surround view or formatter execution.
- Are **not** supported in Razor Pages.
- **Exception filters** apply global policies to unhandled exceptions that occur before the response body has been written to.
- **Result filters** run code immediately before and after the execution of action results. They run only when the action method has executed successfully. They are useful for logic that must surround view or formatter execution.
## **Implementation**
@ -44,7 +44,7 @@ Interfaces for multiple filter stages can be implemented in a single class.
## **Built-in filter attributes**
ASP.NET Core includes built-in *attribute-based* filters that can be subclassed and customized.
ASP.NET Core includes built-in _attribute-based_ filters that can be subclassed and customized.
Several of the filter interfaces have corresponding attributes that can be used as base classes for custom implementations.
Filter attributes:
@ -58,12 +58,12 @@ Filter attributes:
## **Filter scopes**
A filter can be added to the pipeline at one of three *scopes*:
A filter can be added to the pipeline at one of three *scopes*:
- Using an attribute on a controller action. Filter attributes cannot be applied to Razor Pages handler methods.
```cs
// services.AddScoped<CustomActionFilterAttibute>();
// services.AddScoped<CustomActionFilterAttribute>();
[ServiceFilter(typeof(CustomActionFilterAttribute))]
public IActionResult Index()
{
@ -101,14 +101,14 @@ public void ConfigureServices(IServiceCollection services)
When there are multiple filters for a particular stage of the pipeline, scope determines the default order of filter execution. Global filters surround class filters, which in turn surround method filters.
As a result of filter nesting, the *after* code of filters runs in the reverse order of the *before* code. The filter sequence:
As a result of filter nesting, the *after* code of filters runs in the reverse order of the *before* code. The filter sequence:
- The *before* code of global filters.
- The *before* code of controller and Razor Page filters.
- The *before* code of action method filters.
- The *after* code of action method filters.
- The *after* code of controller and Razor Page filters.
- The *after* code of global filters.
- The *before* code of global filters.
- The *before* code of controller and Razor Page filters.
- The *before* code of action method filters.
- The *after* code of action method filters.
- The *after* code of controller and Razor Page filters.
- The *after* code of global filters.
### Cancellation and Short-Circuiting

16
DotNet/ASP.NET/MVC.md
View file

@ -42,7 +42,7 @@ Project
| |-HomeController.cs
|
|- appsettings.json
|- Program.cs --> App entrypoiny
|- Program.cs --> App entry-point
|- Startup.cs --> App config
```
@ -70,7 +70,7 @@ namespace App.Controllers
// GET /Controller/Index
public IActionResult Index()
{
IEnumerable<Entity> enities = _db.Entities;
IEnumerable<Entity> entities = _db.Entities;
return View(Entities); // pass data to the @model
}
@ -83,7 +83,7 @@ namespace App.Controllers
// POST /Controller/Create
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult Create(Entity entity) // recieve data from the @model
public IActionResult Create(Entity entity) // receive data from the @model
{
_db.Entities.Add(entity);
_db.SaveChanges();
@ -104,7 +104,7 @@ namespace App.Controllers
return NotFound();
}
return View(entity); // return pupulated form for updating
return View(entity); // return populated form for updating
}
// POST /Controller/Edit
@ -136,7 +136,7 @@ namespace App.Controllers
return NotFound();
}
return View(entity); // return pupulated form for confirmation
return View(entity); // return populated form for confirmation
}
// POST /Controller/Delete
@ -197,7 +197,7 @@ In `View.cshtml`;
<div class="col-8">
<input asp-for="IntProp" class="form-control"/>
<span asp-validation-for="IntProp" class="text-danger"></span> // error message displyed here
<span asp-validation-for="IntProp" class="text-danger"></span> // error message displayed here
</div>
</div>
</form>
@ -230,7 +230,7 @@ namespace App.Controllers
// GET /Controller/Index
public IActionResult Index()
{
IEnumerable<Entity> enities = _db.Entities;
IEnumerable<Entity> entities = _db.Entities;
return View(Entities); // pass data to the @model
}
@ -243,7 +243,7 @@ namespace App.Controllers
// POST /Controller/Create
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult Create(Entity entity) // recieve data from the @model
public IActionResult Create(Entity entity) // receive data from the @model
{
if (ModelState.IsValid) // all rules in model have been met
{

14
DotNet/ASP.NET/Middleware.md
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@ -7,13 +7,13 @@ Middleware is software that's assembled into an app pipeline to handle requests
Request delegates are used to build the request pipeline. The request delegates handle each HTTP request.
Request delegates are configured using [Run][Run_docs], [Map][Map_docs], and [Use][Use_docs] extension methods.
Request delegates are configured using [Run][Run_docs], [Map][Map_docs], and [Use][Use_docs] extension methods.
An individual request delegate can be specified in-line as an anonymous method (called in-line middleware), or it can be defined in a reusable class.
These reusable classes and in-line anonymous methods are *middleware*, also called *middleware components*.
These reusable classes and in-line anonymous methods are *middleware*, also called *middleware components*.
Each middleware component in the request pipeline is responsible for invoking the next component in the pipeline or short-circuiting the pipeline.
When a middleware short-circuits, it's called a *terminal middleware* because it prevents further middleware from processing the request.
When a middleware short-circuits, it's called a *terminal middleware* because it prevents further middleware from processing the request.
[Use_docs]: https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.builder.useextensions.use
[Run_docs]: https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.builder.runextensions.run
@ -166,10 +166,10 @@ namespace <App>
The middleware class **must** include:
- A public constructor with a parameter of type [RequestDelegate][RequestDelegate_docs].
- A public method named `Invoke` or `InvokeAsync`. This method must:
- Return a `Task`.
- Accept a first parameter of type [HttpContext][HttpConrext_Docs].
- A public constructor with a parameter of type [RequestDelegate][RequestDelegate_docs].
- A public method named `Invoke` or `InvokeAsync`. This method must:
- Return a `Task`.
- Accept a first parameter of type [HttpContext][HttpConrext_Docs].
[RequestDelegate_docs]: https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.http.requestdelegate
[HttpConrext_Docs]: https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.http.httpcontext

8
DotNet/ASP.NET/REST API.md
View file

@ -178,8 +178,8 @@ namespace <Namespace>.Repo
## Data Transfer Objects (DTOs)
A **DTO** is an object that defines how the data will be sent and recieved over the network (usually as JSON).
Without a DTO the JSON response (or reqest) could contain irrilevant, wrong or unformatted data.
A **DTO** is an object that defines how the data will be sent and received over the network (usually as JSON).
Without a DTO the JSON response (or request) could contain irrelevant, wrong or unformatted data.
Moreover, by decoupling the JSON response from the actual data model, it's possible to change the latter without breaking the API.
DTOs must be mapped to the internal methods.
@ -236,11 +236,11 @@ namespace <Namespace>.Profiles
## Controller (No View)
Uses [Dependency Injection](https://en.wikipedia.org/wiki/Dependency_injection) to recieve a suitable implementation of `IEntityRepo`,
Uses [Dependency Injection](https://en.wikipedia.org/wiki/Dependency_injection) to receive a suitable implementation of `IEntityRepo`,
### Service Lifetimes
- `AddSignleton`: same for every request
- `AddSingleton`: same for every request
- `AddScoped`: created once per client
- `Transient`: new instance created every time

14
DotNet/ASP.NET/Razor Pages.md
View file

@ -33,7 +33,7 @@ Project
| |- ...
|
|- appsettings.json --> application settings
|- Program.cs --> App entrypoint
|- Program.cs --> App entry-point
|- Startup.cs
```
@ -88,17 +88,17 @@ namespace App.Pages
{
private readonly ApplicationDbContext _db; // EF DB Context
// Get DBContex through DI
// Get DBContext through DI
public IndexModel(ApplicationDbContext db)
{
_db = db;
}
[BindProperty] // assumed to be recieved on POST
[BindProperty] // assumed to be received on POST
public IEnumerable<Entity> Entities { get; set; }
// HTTP Method Handler
public aysnc Task OnGet()
public async Task OnGet()
{
// get data from DB (example operation)
Entities = await _db.Entities.ToListAsync();
@ -131,12 +131,12 @@ Rules:
- URL maps to a physical file on disk
- Razor paged needs a root folder (Default "Pages")
- file extension not included in URL
- `Index.cshtml` is enrtypoint and default document (missing file in URL redirects to index)
- `Index.cshtml` is entry-point and default document (missing file in URL redirects to index)
| URL | Maps TO |
|------------------------|----------------------------------------------------|
| www.domain.com | /Pages/Index.cshtml |
| www.doamin.com/Index | /Pages/Index.html |
| www.domain.com/Index | /Pages/Index.html |
| www.domain.com/Account | /Pages/Account.cshtml, /Pages/Account/Index.cshtml |
## Data Validation
@ -179,7 +179,7 @@ In `View.cshtml`;
<div class="col-8">
<input asp-for="IntProp" class="form-control"/>
<span asp-validation-for="IntProp" class="text-danger"></span> // error message displyed here
<span asp-validation-for="IntProp" class="text-danger"></span> // error message displayed here
</div>
</div>
</form>

12
DotNet/ASP.NET/Razor Syntax.md
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@ -10,14 +10,14 @@
@* razor comment *@
// substituite @variable with it's value
// substitute @variable with it's value
<tag>@variable</tag>
@{
// razor code block
// can contain C# or HTML
Model // acces to passed @model (MVC)
Model // access to passed @model (MVC)
}
@if (condition) { }
@ -58,7 +58,7 @@ The first parameter after `@addTagHelper` specifies the Tag Helpers to load (`*`
It's possible to disable a Tag Helper at the element level with the Tag Helper opt-out character (`!`)
```cshtml
<!-- disable email vaidation -->
<!-- disable email validation -->
<!span asp-validation-for="Email" ></!span>
```
@ -86,7 +86,7 @@ The `@tagHelperPrefix` directive allows to specify a tag prefix string to enable
@Model.EntityProp
<from>
// use the property as the label, eventyally w/ [DysplayName("...")]
// use the property as the label, eventually w/ [DisplayName("...")]
<label asp-for="EntityProp"></label>
@Html.LabelFor()
@ -131,7 +131,7 @@ In `View.cs`
<form asp-controller="Controller" asp-action="PostAction">
<select asp-for"EntityId" asp-items="Model.Enities">
<select asp-for"EntityId" asp-items="Model.Entities">
</select>
<button type="submit">Send<button>
@ -145,7 +145,7 @@ public IActionResult GetAction()
{
var vm = new ViewModel();
vm.Entities = new SelectList(_context.Enities, "Id", "Text"); // fill SelectList
vm.Entities = new SelectList(_context.Entities, "Id", "Text"); // fill SelectList
vm.EntityId = value; // set selected option (OPTIONAL)
return View(vm);

6
DotNet/ASP.NET/SignalR.md
View file

@ -52,9 +52,9 @@ public class CustomHub : Hub
return Clients.Caller.SendAsync("CLientMethod", args);
// trigger function on clients of a group and pass args to it
return Clients.Group("GoupName").SendAsync("CLientMethod", args);
return Clients.Group("GroupName").SendAsync("CLientMethod", args);
// other opeations
// other operations
}
}
```
@ -149,7 +149,7 @@ Reference the SignalR JavaScript client in the `<script>` element. For example:
const connection = new signalR.HubConnectionBuilder()
.withUrl("/hub/endpoint")
.configureLogging(signalR.LogLevel.Information)
.withAutomaticreconnect() // optional
.withAutomaticReconnect() // optional
.build();
// async/await connection start

4
DotNet/ASP.NET/WebForms.md
View file

@ -2,7 +2,7 @@
## `Page.aspx`
The fist loaded page is `Default.aspx` and its undelying code.
The fist loaded page is `Default.aspx` and its underlying code.
```html
<!-- directive -->
@ -76,7 +76,7 @@ namespace Project
}
protected void Control_Event(object sender, EventAtgs e)
protected void Control_Event(object sender, EventArgs e)
{
// actions on event trigger
}

26
DotNet/ASP.NET/WebForms/Page.aspx.cs.md Normal file
View file

@ -0,0 +1,26 @@
# Page.aspx.cs
```cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace Project
{
public partial class Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Control_Event(object sender, EventArgs e)
{
// actions on event trigger
}
}
}
```

58
DotNet/ASP.NET/WebForms/Page.aspx.md Normal file
View file

@ -0,0 +1,58 @@
# Page.aspx
The fist loaded page is `Default.aspx` and its underlying code.
```html
<!-- directive -->
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="Project.Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"> <!-- XML Namespace -->
<head runat="server"> <!-- runat: handle as ASP code -->
<title></title>
</head>
<body>
<!-- web forms require a form tag to be the whole body -->
<form id="form1" runat="server"> <!-- runat: handle as ASP code -->
<div>
</div>
</form>
</body>
</html>
```
## ASP.NET Directives
### Page Directive
```cs
<%@ Page Language="C#" // define language used (can be C# or VB)
AutoEventWireup="true" // automatically create and setup event handlers
CodeBehind="Default.aspx.cs" // define the underlying code file
Inherits="EmptyWebForm.Default" %>
```
## Web Controls
```xml
<asp:Control ID="" runat="server" ...></asp:Control>
<!-- Label: empty text will display ID, use empty space as text for empty label -->
<asp:Label ID="lbl_" runat="server" Text=" "></asp:Label>
<!-- TextBox -->
<asp:TextBox ID="txt_" runat="server"></asp:TextBox>
<!-- Button -->
<asp:Button ID="btn_" runat="server" Text="ButtonText" OnClick="btn_Click" />
<!-- HyperLink -->
<asp:HyperLink ID="lnk_" runat="server" NavigateUrl="~/Page.aspx">LINK TEXT</asp:HyperLink>
<!-- LinkButton: POstBackEvent reloads the page -->
<asp:LinkButton ID="lbtHome" runat="server" PostBackUrl="~/Page.aspx" OnClick="lbt_Click">BUTTON TEXT</asp:LinkButton>
<!-- Image -->
<asp:Image ID="img_" runat="server" ImageUrl="~/Images/image.png"/>
<!-- ImageButton -->
<asp:ImageButton ID="imb_" runat="server" ImageUrl="~/Images/image.png" PostBackUrl="~/Page.aspx"/>
<!-- SqlSataSource; connection string specified in Web.config -->
<asp:SqlDataSource ID="sds_" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="SQL Query"></asp:SqlDataSource>
```

2
DotNet/C#/Async Programming.md
View file

@ -160,4 +160,4 @@ protected async void MyButton_Click(object sender, EventArgs e)
// We may actually be on another *thread*, but we have the same ASP.NET request context.
Response.Write("File downloaded!");
}
```
```

40
DotNet/C#/C# Collections.md
View file

@ -2,9 +2,9 @@
## Arrays
An array is an object that contains multiple elements of a particular type. The number of elements is fixed for the lifetime of the array, so it must be specied when the array is created.
An array is an object that contains multiple elements of a particular type. The number of elements is fixed for the lifetime of the array, so it must be specified when the array is created.
An array type is always a reference type, regardless of the element type. Nonetheless, the choice between reference type and value type elements makes a significant difference in an array’s behavior.
An array type is always a reference type, regardless of the element type. Nonetheless, the choice between reference type and value type elements makes a significant difference in an array's behavior.
```cs
type[] array = new type[dimension];
@ -14,9 +14,9 @@ type[] array = {value1, value2, ..., valueN}; // initializer
var array = new type[] {value1, value2, ..., valueN}; // initializer (var type needs new operator)
var array = new[] {value1, value2, ..., valueN}; // initializer w/ element type inference (var type needs new operator), can be used as method arg
array[index]; // value acces
array[index] = value; // value assignement
array.Lenght; // dimension of the array
array[index]; // value access
array[index] = value; // value assignment
array.Length; // dimension of the array
// from IEnumerable<T>
array.OfType<Type>(); // filter array based on type, returns IEnumerable<Type>
@ -27,17 +27,17 @@ array.OfType<Type>(); // filter array based on type, returns IEnumerable<Type>
```cs
// overloaded search methods
Array.IndexOf(array, item); // return index of searched item in passed array
Array.LastIndexOf(array, item); // return index of searched item staring from the end of the arrary
Array.LastIndexOf(array, item); // return index of searched item staring from the end of the array
Array.FindIndex(array, Predicate<T>) // returns the index of the first item matching the predicate (can be lambda function)
Array.FindLastIndex(array, Predicate<T>) // returns the index of the last item matching the predicate (can be lambda function)
Array.Find(array, Predicate<T>) // returns the value of the first item matching the predicate (can be lambda function)
Array.FindLast(array, Predicate<T>) // returns the value of the last item matvhing the predicate (can be lambda function)
Array.FindLast(array, Predicate<T>) // returns the value of the last item matching the predicate (can be lambda function)
Array.FindAll(array, Predicate<T>) // returns array of all items matching the predicate (can be lambda function)
Array.BinarySearch(array, value) // Searches a SORTED array for a value, using a binary search algorithm; retuns the index of the found item
Array.BinarySearch(array, value) // Searches a SORTED array for a value, using a binary search algorithm; returns the index of the found item
Array.Sort(array);
Array.Reverse(array); // reverses the order of array elements
Array.Clear(start_index, x); //removes reference to x elements starting at start index. Dimension of array uncanged (cleared elements value is set tu null)
Array.Clear(start_index, x); //removes reference to x elements starting at start index. Dimension of array unchanged (cleared elements value is set tu null)
Array.Resize(ref array, target_dimension); //expands or shrinks the array dimension. Shrinking drops trailing values. Array passed by reference.
// Copies elements from an Array starting at the specified index and pastes them to another Array starting at the specified destination index.
@ -78,8 +78,8 @@ type[,] matrix = new type[n, m]; // n * m matrix
type[,] matrix = {{}, {}, {}, ...}; // {} for each row to initialize
type[, ,] tensor = new type[n, m, o] // n * m * o tensor
matrix.Length; // total numeber of elements (n * m)
matrix.GetLenght(int dimension); // get the size of a particular direction
matrix.Length; // total number of elements (n * m)
matrix.GetLength(int dimension); // get the size of a particular direction
// row = 0, column = 1, ...
```
@ -102,13 +102,13 @@ list.Insert(index, item); // insert an item at the specified index
list.InsertRange(index, item); // insert items at the specified index
list.IndexOf(item); // return index of searched item in passed list
list.LastIndexOf(item); // return index of searched item staring from the end of the arrary
list.LastIndexOf(item); // return index of searched item staring from the end of the array
list.FindIndex(Predicate<T>) // returns the index of the first item matching the predicate (can be lambda function)
list.FindLastIndex(Predicate<T>) // returns the index of the last item matching the predicate (can be lambda function)
list.Find(Predicate<T>) // returns the value of the first item matching the predicate (can be lambda function)
list.FindLast(Predicate<T>) // returns the value of the last item matvhing the predicate (can be lambda function)
list.FindLast(Predicate<T>) // returns the value of the last item matching the predicate (can be lambda function)
list.FindAll(Predicate<T>) // returns list of all items matching the predicate (can be lambda function)
list.BinarySearch(value) // Searches a SORTED list for a value, using a binary search algorithm; retuns the index of the found item
list.BinarySearch(value) // Searches a SORTED list for a value, using a binary search algorithm; returns the index of the found item
list.Remove(item); // remove item from list
list.RemoveAt(index); // remove item at specified position
@ -138,7 +138,7 @@ When a `yield return` statement is reached, the current location in code is reme
It's possible to use a `yield break` statement or exception to end the iteration.
**Note**: Since an iteartor returns an `IEnumerable<T>` is can be used to implement a `GetEnumerator()`.
**Note**: Since an iterator returns an `IEnumerable<T>` is can be used to implement a `GetEnumerator()`.
```cs
// simple iterator
@ -159,7 +159,7 @@ Exposes the enumerator, which supports a simple iteration over a collection of a
```cs
public interface IEnumerable<out T> : IEnumerable
{
IEnumerator<T> GetEnumerator(); // retrun an enumerator
IEnumerator<T> GetEnumerator(); // return an enumerator
}
// iterate through a collection
@ -227,7 +227,7 @@ Span<T> slice = array[start..end];
ReadOnlySpan<T> slice = array[start..end];
```
## [Dictioanaries](https://docs.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2)
## [Dictionaries](https://docs.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2)
[ValueCollection](https://docs.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2.valuecollection)
[KeyCollection](https://docs.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2.keycollection)
@ -258,10 +258,10 @@ Dictionary<TKey, TValue> dict =
}
// indexer access
dict[key]; // read value associted with key (throws KeyNotFoundException if key does not exist)
dict[key] = value; // modify value associted with key (throws KeyNotFoundException if key does not exist)
dict[key]; // read value associated with key (throws KeyNotFoundException if key does not exist)
dict[key] = value; // modify value associated with key (throws KeyNotFoundException if key does not exist)
dict.Count; // numer of key-value pair stored in the dict
dict.Count; // number of key-value pair stored in the dict
dict.Keys; // Dictionary<TKey,TValue>.KeyCollection containing the keys of the dict
dict.Values; // Dictionary<TKey,TValue>.ValueCollection containing the values of the dict

10
DotNet/C#/LINQ.md
View file

@ -11,7 +11,7 @@ LINQ to Objects will be used when any `IEnumerable<T>` is specified as the sourc
### Query Expressions
All query expressions are required to begin with a `from` clause, which specifies the source of the query.
The final part of the query is a `select` (or `group`) clause. This determines the final output of the query and its sytem type.
The final part of the query is a `select` (or `group`) clause. This determines the final output of the query and its system type.
```cs
// query expression
@ -21,10 +21,10 @@ var result = from item in enumerable select item;
var result = from item in enumerable where condition select item;
// ordering
var result = from item in enumerable orderby item.property select item; // ordered IEnumerble
var result = from item in enumerable orderby item.property select item; // ordered IEnumerable
// let clause, assign expression to variable to avoid re-evaluetion on each cycle
var result = from item in enumerable let tmp = <sub-expr> ... // BEWARE: compiled code has a lot of overhead to satisfy let caluse
// let clause, assign expression to variable to avoid re-evaluation on each cycle
var result = from item in enumerable let tmp = <sub-expr> ... // BEWARE: compiled code has a lot of overhead to satisfy let clause
// grouping (difficult to re-implement to obtain better performance)
var result = from item in enumerable group item by item.property; // returns IEnumerable<IGrouping<TKey,TElement>>
@ -71,7 +71,7 @@ IEnumerable<T>.Any(Func<T, bool> predicate); // check if condition is true for
IEnumerable<T>.Concat(IEnumerable<T> enumerable);
// Applies a specified function to the corresponding elements of two sequences, producing a sequence of the results.
IEnumerable<TFirst>.Zip(IEnumerable<TSecond> enumerable, Func<TFirst, TSecoind, TResult> func);
IEnumerable<TFirst>.Zip(IEnumerable<TSecond> enumerable, Func<TFirst, TSecond, TResult> func);
IEnumerable<TFirst>.Zip(IEnumerable<TSecond> enumerable); // Produces a sequence of tuples with elements from the two specified sequences.
```

4
DotNet/C#/Reactive Extensions.md
View file

@ -3,7 +3,7 @@
The **Reactive Extensions** for .NET, or **Rx**, are designed for working with asynchronous and event-based sources of information.
Rx provides services that help orchestrate and synchronize the way code reacts to data from these kinds of sources.
Rx’s fundamental abstraction, `IObservable<T>`, represents a sequence of items, and its operators are defined as extension methods for this interface.
Rx's fundamental abstraction, `IObservable<T>`, represents a sequence of items, and its operators are defined as extension methods for this interface.
This might sound a lot like LINQ to Objects, and there are similarities, not only does `IObservable<T>` have a lot in common with `IEnumerable<T>`, but Rx also supports almost all of the standard LINQ operators.
@ -12,7 +12,7 @@ of an Rx source demand to be given the next item. Instead, Rx uses a *push* mode
Because Rx implements standard LINQ operators, it's possible to write queries against a live source. Rx goes beyond standard LINQ, adding its own operators that take into account the temporal nature of a live event source.
## Foundamental Interfaces
## Fundamental Interfaces
The two most important types in Rx are the `IObservable<T>` and `IObserver<T>` interfaces.
They are important enough to be in the System namespace. The other parts of Rx are in the `System.Reactive` NuGet package.

6
DotNet/Database/ADO.NET.md
View file

@ -22,7 +22,7 @@ The `ADO.NET` classes are found in `System.Data.dll`, and are integrated with th
### [SQLite](https://www.connectionstrings.com/sqlite/)
- Basic: `Data Source: path\to\db.sqlite3; Version=3;`
- In-Memory Dataabse: `Data Source=:memory:; Version=3; New=True`
- In-Memory Database: `Data Source=:memory:; Version=3; New=True`
- With Password: `Data Source: path\to\db.sqlite3; Version=3; Password=<password>`
## Connection to DB
@ -59,7 +59,7 @@ namespace <namespace>
using (SqlConnection connection = new SqlConnection())
{
connection.ConnectionString = connectionString.ConnectionString;
connection.Open(); // start comunication w/ sql server
connection.Open(); // start communication w/ sql server
}
// more compact
@ -106,7 +106,7 @@ using (SqlDataReader cursor = command.ExecuteReader()) // object to get data fr
// check for null before retrieving the value
if(!cursor.IsDBNull(n))
{
sqlreader.Get<SystemType>(index); // retrieve data form the n-th column
cursor.Get<SystemType>(index); // retrieve data form the n-th column
}
}
}

2
DotNet/Database/EntityFramework.md
View file

@ -67,7 +67,7 @@ namespace <Project>.Model
Create & Update DB Schema if necessary.
In Packge Manager Shell:
In Package Manager Shell:
```ps1
PM> Add-Migration <migration_name>

4
DotNet/Godot/Scripting.md
View file

@ -30,6 +30,8 @@ public class NodeName : NodeType
{
}
public void _OnEmitterSignal() { }
}
```
@ -92,7 +94,7 @@ public override void _Ready()
The safest way to delete a node is by using `Node.QueueFree()`. This erases the node safely during idle.
### Instantiting Scenes
### Instantiating Scenes
```cs
// STEP 1: load the scene

28
DotNet/Unity/Collisions.md
View file

@ -2,14 +2,14 @@
## Rigidbody Component
Enables physycs on the game objects.
Enables physics on the game objects.
Rigidbodies collide with other objects instead of going through them.
Avoid obejct rotation on colisions:
Avoid object rotation on collisions:
1. Assign `Rigidbody` component to object
2. Enable Freeze Rotaion in Rigidbody > Constraints
2. Enable Freeze Rotation in Rigidbody > Constraints
```cs
using UnityEngine;
@ -21,19 +21,19 @@ public class GameObject : MonoBehaviour {
void Start()
{
rigidbody = GetComponenet<Rigidbody>(); // get rigidbody reference
rigidbody = GetComponent<Rigidbody>(); // get rigidbody reference
}
void Update()
{
}
// FixedUpdate is calles every x seconds (not influenced by FPS instability)
// used for physics calculations which sould be FPS independant
// FixedUpdate is calls every x seconds (not influenced by FPS instability)
// used for physics calculations which should be FPS independent
void FixedUpdate()
{
Time.fixedDeltaTime; // fixed amount of time
Time.timeDelta; // if called inside FIxedUpadate() behaves like fixedDeltaTime
Time.timeDelta; // if called inside FIxedUpdate() behaves like fixedDeltaTime
}
}
@ -44,8 +44,8 @@ public class GameObject : MonoBehaviour {
Enable `Is Trigger` to register the collision but avoid blocking the movement of the objects.
The trigger can generate a event to signal the contact with the object.
One of the collidng GameObjects *must have* the `Rigidbody` component and the other `Is Trigger` enabled.
To detect the collison but avoid computing the physycs `Is Kinematic` must be enabled in the `Rigidbody` component.
One of the colliding GameObjects *must have* the `Rigidbody` component and the other `Is Trigger` enabled.
To detect the collision but avoid computing the physics `Is Kinematic` must be enabled in the `Rigidbody` component.
```cs
using UnityEngine;
@ -57,21 +57,21 @@ public class GameObject : MonoBehaviour {
void Start()
{
rigidbody = GetComponenet<Rigidbody>(); // get rigidbody reference
rigidbody = GetComponent<Rigidbody>(); // get rigidbody reference
}
// FixedUpdate is calles every x seconds (not influenced by FPS instability)
// used for physics calculations which sould be FPS independant
// FixedUpdate is calls every x seconds (not influenced by FPS instability)
// used for physics calculations which should be FPS independent
void FixedUpdate()
{
Time.fixedDeltaTime; // fixed amount of time
Time.timeDelta; // if called inside FIxedUpadate() behaves like fixedDeltaTime
Time.timeDelta; // if called inside FixedUpdate() behaves like fixedDeltaTime
}
// called on box collision.
void OnTriggerEnter(Collider triggerCollider) {
// detect a collison with a perticular GameObject(must have a TAG)
// detect a collision with a particular GameObject(must have a TAG)
if (triggerCollider.tag = "tag") {
Destroy(triggerCollider.gameObject); // destroy tagged item on collision
//or

4
DotNet/Unity/Coroutines.md
View file

@ -2,7 +2,7 @@
[Coroutines - Unity manual](https://docs.unity3d.com/Manual/Coroutines.html)
When you call a function, it runs to completion before returning. This effectively means that any action taking place in a function must happen *within a single frame update*; a function call can’t be used to contain a procedural animation or a sequence of events over time.
When you call a function, it runs to completion before returning. This effectively means that any action taking place in a function must happen *within a single frame update*; a function call can't be used to contain a procedural animation or a sequence of events over time.
A coroutine is like a function that has the ability to pause execution and return control to Unity but then to continue where it left off on the following frame.
@ -22,7 +22,7 @@ IEnumerator coroutine()
// or
yeld return StartCoroutine(coroutine()); // wait for anothe coroitine to finish before starting
yeld return StartCoroutine(coroutine()); // wait for another coroutine to finish before starting
}
StartCoroutine(coroutine()); // start the coroutine

6
DotNet/Unity/Input Manager.md
View file

@ -4,7 +4,7 @@ The Input Manager uses the following types of controls:
- **Key** refers to any key on a physical keyboard, such as `W`, `Shift`, or the `space bar`.
- **Button** refers to any button on a physical controller (for example, gamepads), such as the `X` button on an Xbox One controller.
- A **virtual axis** (plural: axes) is mapped to a **control**, such as a button or a key. When the user activates the control, the axis receives a value in the range of `[–1..1]`.
- A **virtual axis** (plural: axes) is mapped to a **control**, such as a button or a key. When the user activates the control, the axis receives a value in the range of `[-1..1]`.
## Virtual axes
@ -30,8 +30,8 @@ The Input Manager uses the following types of controls:
Axis values can be:
- Between `–1` and `1` for joystick and keyboard input. The neutral position for these axes is `0`. Some types of controls, such as buttons on a keyboard, aren’t sensitive to input intensity, so they can’t produce values other than `–1`, `0`, or `1`.
- Mouse delta (how much the mouse has moved during the last frame) for mouse input. The values for mouse input axes can be larger than `1` or smaller than `–1` when the user moves the mouse quickly.
- Between `-1` and `1` for joystick and keyboard input. The neutral position for these axes is `0`. Some types of controls, such as buttons on a keyboard, aren't sensitive to input intensity, so they can't produce values other than `-1`, `0`, or `1`.
- Mouse delta (how much the mouse has moved during the last frame) for mouse input. The values for mouse input axes can be larger than `1` or smaller than `-1` when the user moves the mouse quickly.
```cs
//Define the speed at which the object moves.

4
DotNet/Unity/Prefabs Instantiation.md
View file

@ -1,8 +1,8 @@
# Prefabs
Prefabs are a blueprint for GameObcets and any change made to the prefab is inherited by all it's instances.
Prefabs are a blueprint for GameObjects and any change made to the prefab is inherited by all it's instances.
## Script Instantation
## Script Instantiation
```cs

20
DotNet/Unity/Raycasting.md
View file

@ -1,6 +1,6 @@
# Raycasting Notes
A raycast is conceptually like a laser beam that is fired from a point in space along a particular directuin. Any object making contact with the beam can be detected and reported.
A raycast is conceptually like a laser beam that is fired from a point in space along a particular direction. Any object making contact with the beam can be detected and reported.
## 3D Raycasting
@ -16,13 +16,13 @@ void Update()
hitInfo.transform // transform og the hit object
hitInfo.collider.gameObject // reference to the object hit by the ray
hitInfo.collider.gameObject // reference to the object hit by the ray
hitInfo.normal // normal bector og the hit surface
hitInfo.normal // normal vector og the hit surface
hitInfo.point // actual point of collision
// static method, object must haave a collider dot the collision to happen, returns a BOOL
// static method, object must have a collider dot the collision to happen, returns a BOOL
Physics.Raycast(ray, out hitInfo); // update hitInfo based on ray collisions
Physics.Raycast(ray, out hitInfo, float maxRayDistance); // limit the ray length
Physics.Raycast(ray, out hitInfo, Mask mask); // specify with which layers the ray can interact, layer must be allpied to object's mask
Physics.Raycast(ray, out hitInfo, Mask mask); // specify with which layers the ray can interact, layer must be applied to object's mask
Physics.Raycast(ray, out hitInfo, Mask mask, QueryTriggerInteraction.Ignore); // ignore collision if "is trigger" is enabled on other objects
// detect a collision
@ -30,12 +30,12 @@ void Update()
{
//collision happened
// draw the ray ingame for debuggng
// draw the ray in game for debugging
Debug.DrawLine(ray.origin, hitInfo.point, Color.red); // draw red line if collision happens
}
else
{
Debug.DrawLine(ray.origin, ray.origin + ray.direction * 100, Color.blue); // draw blue line if collision happens, arrival point is 100 units from the origin sinche the ray goes to infinity
Debug.DrawLine(ray.origin, ray.origin + ray.direction * 100, Color.blue); // draw blue line if collision happens, arrival point is 100 units from the origin since the ray goes to infinity
}
}
```
@ -47,8 +47,8 @@ public Camera gameCamera;
void Update()
{
// ray goint ftom cametra through a screen point
Ray ray = gameCamera.ScreenPointToRay(Input.mousePosition); // Input.mousePosition is the postion of the mouse in pixels (screen points)
// ray going from camera through a screen point
Ray ray = gameCamera.ScreenPointToRay(Input.mousePosition); // Input.mousePosition is the position of the mouse in pixels (screen points)
RaycastHit hitInfo; // place pointed by the mouse
Physics.Raycast(ray, out hitInfo) // update pointed position
@ -61,12 +61,12 @@ void Update()
void Start()
{
Physisc2D.queriesStartColliders = false; // avoid collision with collider of the ray generator gameObject
Physics2D.queriesStartColliders = false; // avoid collision with collider of the ray generator gameObject
}
void Update()
{
// returns a RaycastHit2D, needs an origin and direction separatedly
// returns a RaycastHit2D, needs an origin and direction separately
Raycast2D hitInfo = Physics2D.Raycast(Vector2 origin, Vector2 direction);
Raycast2D hitInfo = Physics2D.Raycast(Vector2 origin, Vector2 direction, float maxRayDistance);
Raycast2D hitInfo = Physics2D.Raycast(Vector2 origin, Vector2 direction, float maxRayDistance);

28
DotNet/Unity/Scripting.md
View file

@ -24,25 +24,25 @@ public class ClassName : MonoBehaviour {
Time.deltaTime; // time since last frame
}
// FixedUpdate is calles every x seconds (not influenced by FPS instability)
// used for physics calculations which sould be FPS independant
// FixedUpdate is calls every x seconds (not influenced by FPS instability)
// used for physics calculations which should be FPS independent
void FixedUpdate()
{
Time.fixedDeltaTime; // fixed amount of time
Time.timeDelta; // if called inside FIxedUpadate() behaves like fixedDeltaTime
Time.timeDelta; // if called inside FIxedUpdate() behaves like fixedDeltaTime
}
}
```
### Script comunication
### Script communication
Referencing data in a sctipt from another.
Referencing data in a script from another.
```cs
//example of a script to be referenced in another
Using System;
public class Player : MonoBheaviour {
public class Player : MonoBehaviour {
public float health = 10;
public event Action OnPlayerDeath; //event of type Action, needs using System
@ -55,7 +55,7 @@ public class Player : MonoBheaviour {
if (health <= 0) {
if (OnPlayerDeath != null) {
OnPleyerDeath(); // invoke Action (if no subscribers event will be NULL, can cause errors)
OnPlayerDeath(); // invoke Action (if no subscribers event will be NULL, can cause errors)
}
Destroy(GameObject); // needs to be notified
@ -68,7 +68,7 @@ public class Player : MonoBheaviour {
// example of script needing a reference to another
public class GameUI : MonoBehaviour {
Player player; //instance of referenced GameObject to be founf by its type
Player player; //instance of referenced GameObject to be found by its type
void Start(){
GameObject playerObj = GameObject.Find("Player"); //reference to game object
@ -77,7 +77,7 @@ public class GameUI : MonoBehaviour {
player = FindObjectOfType<Player>(); // get reference to an object
// on event invocation all subscribet methods will be called
// on event invocation all subscriber methods will be called
player.OnPlayerDeath += GameOver; // subscribe method to event
}
@ -85,7 +85,7 @@ public class GameUI : MonoBehaviour {
DrawHealthBar(plyer.health); // call method passing data of player GameObject
}
void DrawHealthbar(float playerHealth) {
void DrawHealthBar(float playerHealth) {
// implementation
}
@ -100,9 +100,9 @@ public class GameUI : MonoBehaviour {
### 2D Screen Measures
Aspect Ratio = `(screen_width [px]) / (screen_height [px])`
Orhograpic Size `[world units]` = `(screen_height [world units] / 2)`
Aspect Ratio * Orhograpic Size = `(screen_width [world units] / 2)`
Screen Width `[world units]` = `(AspectRatio * OrhograpicSize * 2)`
Orthographic Size `[world units]` = `(screen_height [world units] / 2)`
Aspect Ratio * Orthographic Size = `(screen_width [world units] / 2)`
Screen Width `[world units]` = `(AspectRatio * OrthographicSize * 2)`
```cs
screenWidth = Camera.main.aspect * Camera.main.orthographicSize * 2;
@ -123,7 +123,7 @@ public class ScriptableObjectName : ScriptableObject {
### Game Object Serialization
```c#
[SeralizeField] type variable; //access game object from code
[SerializeField] type variable; //access game object from code
```
### Game Object Data Access

22
DotNet/Unity/Vector, Tranfrorm, Space.md
View file

@ -1,4 +1,4 @@
# Vector, Tranfrorm, Space
# Vector, Transform, Space
## Vector2, Vector3, Vector4
@ -33,8 +33,8 @@ Vector3.one // Vector3(1, 1, 1)
### Operations
```cs
Vector3(x, y, z) * n = Vecotr3(xn, yn, yz);
Vector3(x, y, z) / n = Vecotr3(x / n, y / n, y / z);
Vector3(x, y, z) * n = Vector3(xn, yn, yz);
Vector3(x, y, z) / n = Vector3(x / n, y / n, y / z);
Vector3(x1, y1, z1) + Vector3(x2, y2, z2) = Vector3(x1 + x2, y1 + y2, z1 + z2);
Vector3(x1, y1, z1) - Vector3(x2, y2, z2) = Vector3(x1 - x2, y1 - y2, z1 - z2);
@ -54,11 +54,11 @@ MovementInFrame = Speed * timeSinceLastFrame
[Transform Docs](https://docs.unity3d.com/ScriptReference/Transform.html)
```cs
// propetries
transfrom.position // Vector3 - global position
transfrom.localPosition // Vector3 - local position
// properties
transform.position // Vector3 - global position
transform.localPosition // Vector3 - local position
transform.rotation // Quaternion - global rotation
transfrom.parent // Transform - parent of the object
transform.parent // Transform - parent of the object
transform.localScale = Vector3; // set object dimensions
@ -67,21 +67,21 @@ transform.Rotate(Vector3 * Time.deltaTime * speed, Space); // set rotation usin
transform.Translate(Vector3 * Time.deltaTime * speed, Space); // set movement in selected space
```
### Local, GLobal & Object Spcace
### Local, GLobal & Object Space
**Local Space**: Applies transformation relative to the *local* coordinate system (`Space.Self`).
**Global Space**: Applies transformation relative to the *world* coordinate system (`Space.World`)
### Parenting
Changing the parent will make position, scale and rotation of the child object retalive to the parent but keep the world space's position, rotation and scale the same.
Changing the parent will make position, scale and rotation of the child object relative to the parent but keep the world space's position, rotation and scale the same.
Setting the parentele by script:
```cs
public class ParentScript : MonoBehaviour {
public Transform childTransform; // reference to the child object transfrom
public Transform childTransform; // reference to the child object transform
childTrandform.parent = transfrom; // when evaluated at runtime sets current object as parent of another
childTransform.parent = transform; // when evaluated at runtime sets current object as parent of another
}
```

6
DotNet/Xamarin/App.xaml.md
View file

@ -13,7 +13,7 @@ The word *winfx* refers to a name once used for the .NET Framework 3.0, which in
The `x:Class` attribute can appear only on the root element of a XAML file. It specifies the .NET namespace and name of a derived class. The base class of this derived class is the root element.
In other words, this `x:Class` specification indicates that the `App` class in the `AppName` namespace derives from `Application`.
That’s exactly the same information as the `App` class definition in the `App.xaml.cs` file.
That's exactly the same information as the `App` class definition in the `App.xaml.cs` file.
```xml
<?xml version="1.0" encoding="utf-8" ?>
@ -31,7 +31,7 @@ That’s exactly the same information as the `App` class definition in the `App.
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="AppName.App">
<!-- collection of shared resources definiions -->
<!-- collection of shared resources definitions -->
<Application.Resources>
<!-- Application resource dictionary -->
@ -42,7 +42,7 @@ That’s exactly the same information as the `App` class definition in the `App.
<!-- define a reusable style -->
<Style x:Key="Style Name" TargetType="Element Type">
<!-- set poperties of the style -->
<!-- set properties of the style -->
<Setter Property="PropertyName" Value="PropertyValue">
</Style>

8
DotNet/Xamarin/Page.xaml.md
View file

@ -52,7 +52,7 @@ The term *view* in Xamarin.Forms denotes familiar types of presentation and inte
- StackLayout: Organizes views linearly, either horizontally or vertically.
- AbsoluteLayout: Organizes views by setting coordinates & size in terms of absolute values or ratios.
- RelativeLayout: Organizes views by setting constraints relative to their parent’s dimensions & position.
- RelativeLayout: Organizes views by setting constraints relative to their parent's dimensions & position.
- Grid: Organizes views in a grid of Rows and Columns
- FlexLayout: Organizes views horizontally or vertically with wrapping.
- ScrollView: Layout that's capable of scrolling its content.
@ -60,7 +60,7 @@ The term *view* in Xamarin.Forms denotes familiar types of presentation and inte
### Grid Layout
```xml
<!-- "<num>*" makes the dimesions proportional -->
<!-- "<num>*" makes the dimensions proportional -->
<Gird.RowDefinitions>
<!-- insert a row in the layout -->
<RowDefinition Height="2*"/>
@ -76,11 +76,11 @@ The term *view* in Xamarin.Forms denotes familiar types of presentation and inte
```xml
<Image Source="" BackgroundColor="" [LayoutPosition]/>
<!-- source contains reference to imagefile in Xamarin.[OS]/Resources/drawable -->
<!-- source contains reference to image file in Xamarin.[OS]/Resources/drawable -->
<!-- box to insert text -->
<Editor Placeholder="placeholder text" [LayoutPosition]/>
<!-- clickable button -->
<Button Text="button text" BackgroundColor="" Clicked="function_to_call" [LayoytPosition]/>
<Button Text="button text" BackgroundColor="" Clicked="function_to_call" [LayoutPosition]/>
```

2
DotNet/Xamarin/ViewModel.cs.md
View file

@ -27,7 +27,7 @@ namespace AppName.ViewModels
field = value;
var args = new PropertyChangedEventArgs(nameof(Property)); // EVENT: let view know that the Property has changed
PropertyChanged?.Invoke(this, args); // Ivoke event to notify the view
PropertyChanged?.Invoke(this, args); // Invoke event to notify the view
}
}
}

40
GraphQL.md
View file

@ -50,8 +50,8 @@ GraphQL comes with a set of default scalar types out of the box:
- `Int`: A signed 32‐bit integer.
- `Float`: A signed double-precision floating-point value.
- `String`: A UTF‐8 character sequence.
- `Boolean`: `true` or `false`.
- `ID`: The ID scalar type represents a unique identifier, often used to refetch an object or as the key for a cache. The ID type is serialized in the same way as a `String`; however, defining it as an `ID` signifies that it is not intended to be human‐readable.
- `Boolean`: `true` or `false`.
- `ID`: The ID scalar type represents a unique identifier, often used to refetch an object or as the key for a cache. The ID type is serialized in the same way as a `String`; however, defining it as an `ID` signifies that it is not intended to be human‐readable.
In most GraphQL service implementations, there is also a way to specify custom scalar types.
@ -63,7 +63,7 @@ Then it's up to the implementation to define how that type should be serialized,
### Enumeration Types
Also called *Enums*, enumeration types are a special kind of scalar that is restricted to a particular set of allowed values.
Also called *Enums*, enumeration types are a special kind of scalar that is restricted to a particular set of allowed values.
This allows to:
@ -85,7 +85,7 @@ enum Type{
Object types, scalars, and enums are the only kinds of types that can be defined in GraphQL.
But when used in other parts of the schema, or in the query variable declarations, it's possible apply additional *type modifiers* that affect **validation** of those values.
It's possible to mark a field as *Non-Null* by adding an exclamation mark, `!` after the type name. This means that the server always expects to return a non-null value for this field, and if it ends up getting a null value that will actually trigger a GraphQL execution error, letting the client know that something has gone wrong.
It's possible to mark a field as *Non-Null* by adding an exclamation mark, `!` after the type name. This means that the server always expects to return a non-null value for this field, and if it ends up getting a null value that will actually trigger a GraphQL execution error, letting the client know that something has gone wrong.
The *Non-Null* type modifier can also be used when defining arguments for a field, which will cause the GraphQL server to return a validation error if a null value is passed as that argument, whether in the GraphQL string or in the variables.
@ -190,7 +190,7 @@ It's aldo possible to pass arguments into scalar fields, to implement data trans
### Fragments
Fragments allow to construct sets of fields, and then include them in queries where thay are needed.
Fragments allow to construct sets of fields, and then include them in queries where that are needed.
The concept of fragments is frequently used to split complicated application data requirements into smaller chunks.
```graphql
@ -236,9 +236,9 @@ fragment fragment on Type{
### Operation Name
The *operation type* is either `query`, `mutation`, or `subscription` and describes what type of operation it's intended to be done. The operation type is required unless when using the *query shorthand syntax*, in which case it's not possible to supply a name or variable definitions for the operation.
The *operation type* is either `query`, `mutation`, or `subscription` and describes what type of operation it's intended to be done. The operation type is required unless when using the *query shorthand syntax*, in which case it's not possible to supply a name or variable definitions for the operation.
The *operation name* is a meaningful and explicit name for the operation. It is only required in multi-operation documents, but its use is encouraged because it is very helpful for debugging and server-side logging. When something goes wrong it is easier to identify a query in thecodebase by name instead of trying to decipher the contents.
The *operation name* is a meaningful and explicit name for the operation. It is only required in multi-operation documents, but its use is encouraged because it is very helpful for debugging and server-side logging. When something goes wrong it is easier to identify a query in the codebase by name instead of trying to decipher the contents.
```graphql
query Operation {
@ -250,9 +250,9 @@ query Operation {
When working with variables, three things need to be done:
1. Replace the static value in the query with `$variableName`
2. Declare `$variableName` as one of the variables accepted by the query
3. Pass `variableName: value` in the separate, transport-specific (usually JSON) variables dictionary
1. Replace the static value in the query with `$variableName`
2. Declare `$variableName` as one of the variables accepted by the query
3. Pass `variableName: value` in the separate, transport-specific (usually JSON) variables dictionary
```graphql
query Operation($var: Type = defaultValue) {
@ -275,8 +275,8 @@ A directive can be attached to a field or fragment inclusion, and can affect exe
The core GraphQL specification includes exactly two directives, which must be supported by any spec-compliant GraphQL server implementation:
- `@include(if: Boolean)` Only include this field in the result if the argument is `true`.
- `@skip(if: Boolean)` Skip this field if the argument is `true`.
- `@include(if: Boolean)` Only include this field in the result if the argument is `true`.
- `@skip(if: Boolean)` Skip this field if the argument is `true`.
Server implementations may also add experimental features by defining completely new directives.
@ -299,12 +299,12 @@ mutation Operation {
### Subscriptions
Open a stable connection with the server to recieve real-time updates on the operations happening.
Open a stable connection with the server to receive real-time updates on the operations happening.
```graphql
subscription Operation {
event { # get notified when event happens
field # data recieved on notification
field # data received on notification
...
}
}
@ -349,7 +349,7 @@ GraphQL allows to request `__typename`, a meta field, at any point in a query to
After being validated, a GraphQL query is executed by a GraphQL server which returns a result that mirrors the shape of the requested query, typically as JSON.
Each field on each type is backed by a function called the *resolver* which is provided by the GraphQL server developer. When a field is executed, the corresponding *resolver* is called to produce the next value.
Each field on each type is backed by a function called the *resolver* which is provided by the GraphQL server developer. When a field is executed, the corresponding *resolver* is called to produce the next value.
If a field produces a scalar value like a string or number, then the execution completes. However if a field produces an object value then the query will contain another selection of fields which apply to that object. This continues until scalar values are reached. GraphQL queries always end at scalar values.
@ -358,7 +358,7 @@ If a field produces a scalar value like a string or number, then the execution c
At the top level of every GraphQL server is a type that represents all of the possible entry points into the GraphQL API, it's often called the *Root* type or the *Query* type.
```graphql
# root types for entrypoints
# root types for entry-points
type Query {
rootField(arg: Type = defValue, ...): Type
@ -378,7 +378,7 @@ type Subscription {
A resolver function receives four arguments:
- `obj` The previous object, which for a field on the root Query type is often not used.
- `args` The arguments provided to the field in the GraphQL query.
- `context` A value which is provided to every resolver and holds important contextual information like the currently logged in user, or access to a database.
- `info` A value which holds field-specific information relevant to the current query as well as the schema details
- `obj` The previous object, which for a field on the root Query type is often not used.
- `args` The arguments provided to the field in the GraphQL query.
- `context` A value which is provided to every resolver and holds important contextual information like the currently logged in user, or access to a database.
- `info` A value which holds field-specific information relevant to the current query as well as the schema details

36
HTML/HTML.md
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@ -85,7 +85,7 @@ The body contains the actual content of the page. Everything that is contained i
## JavaScript
XHTML and older: `<script src="js/scripts.js" type="text/javascript"></script>`
HTML5: `<script src="js/scripts.js"></script>` (HTML5 spect states that `type` attribute is redundant and shoul be omitted)
HTML5: `<script src="js/scripts.js"></script>` (HTML5 spec states that `type` attribute is redundant and should be omitted)
The `<script>` tag is used to define a client-side script (JavaScript).
The `<script>` element either contains scripting statements, or it points to an external script file through the src attribute.
@ -124,18 +124,18 @@ Uses of Validation:
The application should validate all information to make sure that it is complete, free of errors and conforms to the specifications required by the back-end.
It should contain mechanisms to warn users if input is not complete or correct.
It should avoid to send ‘bad’ data to the back-end.
It should avoid to send "bad" data to the back-end.
### Back-End Validation
It should never trust that the front-end has done validation since some clever users can bypass the front-end mechanisms easily.
Back-end services can receive data from other services, not necessarily front-end, that don’t perform validation.
Back-end services can receive data from other services, not necessarily front-end, that don't perform validation.
#### Built-In Validation
Not all browsers validate in the same way and some follow the specs partially. Some browsers don’t have validation at all (older desktop browsers, some mobile browsers).
Apart from declaring validation intention with HTML5 developers don’t have much control over what the browser actually does.
Before using build-in validation make sure that it’s supported by the target browsers.
Not all browsers validate in the same way and some follow the specs partially. Some browsers don't have validation at all (older desktop browsers, some mobile browsers).
Apart from declaring validation intention with HTML5 developers don't have much control over what the browser actually does.
Before using build-in validation make sure that it's supported by the target browsers.
#### Validation with JavaScript
@ -203,7 +203,7 @@ Heading numbers indicates hierarchy, not size.
<h2> Heading 2 </h2>
```
### Fromatted Text
### Formatted Text
With semantic value:
@ -217,7 +217,7 @@ Without semantic value, used as last resort:
## Elements
`<br/>`: Line break (carriage return). It's not good practice to put line breacks inside paragraphs.
`<br/>`: Line break (carriage return). It's not good practice to put line breaks inside paragraphs.
`<hr>`: horizontal rule (line). Used to define a thematic change in the content.
@ -227,7 +227,7 @@ Surround content to turn into links.
```html
<!-- Link to absolute URL -->
<a href="uri/url" title="content-title" taget="_self"> text/image </a>
<a href="uri/url" title="content-title" target="_self"> text/image </a>
<!-- links to relative URL -->
<a href="//example.com">Scheme-relative URL</a>
@ -282,7 +282,7 @@ Surround content to turn into links.
</ul>
```
### Ordered list (numebred list)
### Ordered list (numbered list)
```html
<ol>
@ -306,8 +306,8 @@ Surround content to turn into links.
```html
<table>
<thead> <!-- table intestation (head) row -->
<th></th> <!-- table intestation, one for each column-->
<thead> <!-- table head row -->
<th></th> <!-- table head, one for each column-->
<th></th>
</thead>
<tbody> <!-- table content (body) -->
@ -323,7 +323,7 @@ Surround content to turn into links.
Code | Character
---------|-----------------
`&copy;` | Copyrigth
`&copy;` | Copyright
`&lt;` | less than (`<`)
`&gt;` | greater than (`>`)
`&amp;` | ampersand (`&`)
@ -361,7 +361,7 @@ Used to apply a specific style inline.
## HTML Forms
```html
<form action="data-reciever" target="" method="http-method">
<form action="data-receiver" target="" method="http-method">
<!-- ALL form elements go here -->
</form>
```
@ -404,7 +404,7 @@ Input Attributes:
* `name`: assigns a name to the form control (used by JavaScript and queries)
* `value`: value to be sent to the server when the option is selected
* `id`: identifier for CSS and linking tags
* `checked`: intially selected or not (radiobutton, checkboxes, ...)
* `checked`: initially selected or not (radiobutton, checkboxes, ...)
* `selected`: default selection of a dropdown
### Text Field
@ -434,7 +434,7 @@ Text inputs can display a placeholder text that will disappear as soon as some t
```html
<form>
<label for="identifier">Password:</label>
<input type="passwrod" name="user-password" id="identifier">
<input type="password" name="user-password" id="identifier">
</form>
```
@ -519,7 +519,7 @@ Multi line text input.
</form>
```
`sumbit`: sends the form data to the location specified in the action attribute.
`submit`: sends the form data to the location specified in the action attribute.
`reset`: resets all forms controls to the default values.
### Button
@ -563,7 +563,7 @@ Downsides:
### Email Field
Used to receive a valid e-mail address from the user. Most browsers can validate this without needing javascript.
Older browsers don’t support this input type.
Older browsers don't support this input type.
```html
<form>

6
Java/DAO.md
View file

@ -67,7 +67,7 @@ public interface I<Type>DAO {
## `<Type>DAO`
Class implementing `I<Type>DAO` and handling the comunication with the db.
Class implementing `I<Type>DAO` and handling the communication with the db.
```java
package dao;
@ -80,8 +80,8 @@ public class <Type>DAO implements I<Type>DAO {
private <Type> results;
private Statement statement; // SQL instruction contenitor
private ResultSet rs; // Query results contenitor
private Statement statement; // SQL instruction container
private ResultSet rs; // Query results container
private DB db;
public <Type>DAO() {

24
Java/Java Collection Framework.md
View file

@ -1,16 +1,16 @@
# Java Collection Framework - JCF
All classes that permit the handling of groups of objects constituite the Java Collection Framework.
All classes that permit the handling of groups of objects constitute the Java Collection Framework.
A Collection is a *container* in which several objects are grouped in a *single entity*.
The **Java Collection Framework** is constituited by:
The **Java Collection Framework** is constituted by:
- **Interfaces** the define the operations of a generic collection. They can be split into two categories:
- **Collection**: used to optimize operations of insertion, modification and deletion of elements in a group of objects.
- **Map**: optimized for look-up operations.
- **Classes** that implement the interfaces using different data structures.
- **Algorithms** consistng in methods to operate over a collection.
- **Algorithms** consisting in methods to operate over a collection.
![Java Collection Hierarchy](../.images/java_java-collection-framework.png "Java Collection Hierarchy")
@ -19,12 +19,12 @@ The **Java Collection Framework** is constituited by:
### Collection Functions
```java
boolean add (Object o) e.g., <x>.add (<y>) //append to colelction, false if fails
boolean add (Object o) e.g., <x>.add (<y>) //append to collection, false if fails
boolean add (int index, Object o) //insertion at given index
boolean addAll (Collection c) //appends a collection to another
void clear() //remove items from container
boolean contains (Object o) //true if object is in collection
boolean containsAll (Collection c) //true if all items of collectio are in another
boolean containsAll (Collection c) //true if all items of collection are in another
boolean isEmpty (Object o) e.g., if (<x>.isEmpty()) ... //true if collection is empty
boolean remove (Object o) //remove object from collection
Object remove (int index) //remove object at given index
@ -60,19 +60,19 @@ ArrayList<Type> ArrayListName = new ArrayList<>(); //resizable array (JAVA 1.
ArrayListName.add(item); //append item to collection
ArrayListName.add(index, item); // add item at positon index, shift all item from index and successive towards the end af the ArrayList
ArrayListName.add(index, item); // add item at position index, shift all item from index and successive towards the end af the ArrayList
ArrayListName.set(index, item); // substitute EXISTING item
ArrayListName.get(index); //access to collection item
ArrayListName.remove(item) //remove first occurence of item from collection
ArrayListName.remove(item) //remove first occurrence of item from collection
ArrayListName.remove(index) //remove item at position index
ArrayListName.clear() //emties the ArrayList
ArrayListName.clear() //empties the ArrayList
ArrayListName.contains(object); // check if object is in the ArrayList
ArrayListName.IndexOf(object); // returns the index of the object
ArrayListName.isEmpty(); // check wether the list is empty
ArrayListName.size(); //dimension of the ArrayList
ArrayListName.tirmToSize(); // reduce ArrayList size to minimum needed
// ArrayList size doubles when a reseize is needed.
// ArrayList size doubles when a resize is needed.
//run through to the collection with functional programming (JAVA 1.8+)
ArrayListName.forEach(item -> function(v));
@ -94,7 +94,7 @@ class ClassName implements Comparable<ClassName> {
List<ClassName> list;
//valorize List
Collections.sort(list); //"natuarl" sorting uses compareTo()
Collections.sort(list); //"natural" sorting uses compareTo()
```
Otherwise a `Comparator()` must be implemented:
@ -116,7 +116,7 @@ Comparator<ClassName> comparator = new Comparator<ClassName>() {
List<ClassName> list;
//valorize List
Collections.sort(list, comparator); //"natuarl" sorting uses compareTo()
Collections.sort(list, comparator); //"natural" sorting uses compareTo()
```
`Comparator<T>` and `Conmparable<T>` are functional interfaces
`Comparator<T>` and `Comparable<T>` are functional interfaces

115
Java/Java Web/JSP.md
View file

@ -1,115 +0,0 @@
# Java Server Pages Cheat Sheet
Java embedded in html.
Codice + JSP salvati in file `.war`
[TEMP Notes Source](https://github.com/maboglia/CorsoJava/blob/master/appunti/057_JSP_appunti.md#corso-jsp---le-direttive)
## Directives
Le direttive Le direttive permettono di definire la struttura di tutto il documento JSP. Indicano gli aspetti principali del *servlet* in cui sarà convertito il file JSP.
Sono processati al momento della conversione in servlet, a compile-time.
Le direttive esistenti sono: *page*, *include* e *taglib*.
- `<%@ page attribute="value" %>`
- `<%@ include file="path" %>`
- `<%@ taglib ...%>`
Introdotte dal simbolo `@` possono contenere diversi attributi, in alcuni casi concatenabili come per la direttiva import.
### Attributi Direttiva `Page`
**`import="package.class"`**
Lista di package o classes, separati da virgola, che saranno importati per essere utilizzati nel codice java.
**`session ="true | false"`**
Specifica se la pagina fa parte di una sessione HTTP. Se si inizializza a true, è disponibile l'oggetto implicito sessione.
**`buffer ="dimensione-kb"`**
Specifica la dimensione di un buffer di uscita di tipo stream, per il client.
**`errorPage="url"`**
Specifica una pagina JSP che sarà processata nel caso si verifichi un errore.
**`isErrorPage="true|false"`**
Indica che la pagina è una pagina di errore JSP e può mostrare a video l'output dell'errore verificatosi. Per default è settata false.
**`contentType="MIME-Type"`**, **`contentType="MIME-Type; charset=Character-Set"`**
valore MIME di default è text/html
### Direttiva `Include`
Indica al motore JSP di includere il contenuto del file corrispondente, inserendolo al posto della direttiva nella pagina JSP. Il contenuto del file incluso è analizzato al momento della traduzione del file JSP e si include una copia del file stesso nel servlet generato. Una volta incluso, se si modifica il file non sarà ricompilato nel servlet. Il tipo di file da includere può essere un file html (*statico*) o un file jsp (*dinamico*).
```jsp
<html>
<head>
<title> pagina di prova Direttive </title>
</head>
<body>
<h1>pagina di prova Direttive inclusione</h1>
<%@ include file="/hello_world.html" %>
<%@ include file=”/login.jsp” %>
</body>
</html>
```
### Direttiva `Taglib`
Permette estendere i marcatori di JSP con etichette o marcatori generati dall'utente (etichette personalizzate).
Sintassi: `<%@ taglib uri="taglibraryURI" prefix="tagPrefix" %>`
Esempi librerie standard:
- JSTL core
- JSTL sql
- JSTL function
## Implicit Objects
JSP utilizza gli oggetti impliciti (built-in).
Gli oggetti impliciti sono oggetti istanziati automaticamente dall’ambiente JSP, non dobbiamo preoccuparci di importarli e istanziarli.
Per utilizzarli è sufficiente usare la sintassi `nomeOggetto.nomeMetodo`.
Oggetti disponibili per l’uso in pagine JSP:
- **out**: per scrivere codice HTML nella risposta (System.out di Java)
- **session**: dati specifici della sessione utente corrente
- **request**: richiesta HTTP ricevuta e i suoi attributi, header, cookie, parametri, etc.
- **page**: la pagina e le sue proprietà.
- **config**: dati di configurazione
- **response**: risposta HTTP e le sue proprietà.
- **application**: dati condivisi da tutte le pagine della web application
- **exception**: eventuali eccezioni lanciate dal server; utile per pagine di errore
- **pageContext**: dati di contesto per l’esecuzione della pagina
Gli oggetti impliciti possono essere:
- oggetti legati alla servlet relativa alla pagina JSP
- oggetti legati all’input e all’output della pagina JSP
- oggetti che forniscono informazioni sul contesto in cui la JSP viene eseguita
- oggetti risultanti da eventuali errori
Ambito Definisce dove e per quanto tempo saranno accessibili gli oggetti (oggetti impliciti, JavaBeans, ...):
- di pagina: l'oggetto è accessibile dal servlet che rappresenta la pagina
- di richiesta: l'oggetto viene creato e poi distrutto dopo l'uso
- di sessione: l'oggetto è accessibile durante tutta la sessione
- di applicazione: l'oggetto è accessibile dal servlet che rappresenta la pagina
---
## Code in JSP Page
`<% /* code here */ %>` is used to embed java code in a JSP page.
`<%= var %>` is used to get a value from a variable to be displayed.
### Request Parameters
```java
Type variable = request.getParameter("request_parameter"); // parameter of a GET request
```

2
Java/Java Web/Servlet.md
View file

@ -32,7 +32,7 @@ public class <className> extends HttpServlet {
// POST REQUEST: add stuff to DB, page, ...
doGet(request, response); // return same page with new conted added (default case)
doGet(request, response); // return same page with new content added (default case)
}
}
```

154
Java/Java.md
View file

@ -25,7 +25,7 @@ public static void main (String[] args) {
}
```
### Variable Assignement
### Variable Assignment
`Type variable_1 = <expr>, ..., variable_n = <expr>;`
@ -59,7 +59,7 @@ System.out.printf("string %..", variable);
System.out.println(String.format(format, args));
```
Methods ereditated from C. The value pf the variable substitutes %.
Methods inherited from C. The value pf the variable substitutes %.
`%d` int, `%f` float, `%c` char, `%s` string, `%e` scientific notation.
`%digitNumber.decimalDigitNumber` specifies the space occupied by the output.
@ -81,9 +81,9 @@ scanner.close() //closing of Scanner, releases memory
int variable_int_1 = scanner.nextInt(); //takes integer number
String string_1 = scanner.nextLine(); //takes line of text (\n ends line)
String string_1 = scanner.next(); //takes text (spacec ends word)
String string_1 = scanner.next(); //takes text (space ends word)
double variable_double_1 = scanner.nextDouble(); //takes double decimal number
boolean variable_bool = scanner.netxBoolean(); //takes boolean value
boolean variable_bool = scanner.nextBoolean(); //takes boolean value
//(TRUE, FALSE, true, false, True, False)
```
@ -110,7 +110,7 @@ If not specified int & double are the default types.
### Floating-Point numbers & Precision Calcs
Don't use `==` or `!=` to confront floating value numbers since they use approximation or have a lot of digits.
It's best to check if the difference between two numbers is small enought.
It's best to check if the difference between two numbers is small enough.
For high precision calcs is best to use `BigDecimal`.
### Type Conversion (casting) & Type checking
@ -126,7 +126,7 @@ Every primitive type has a corresponding wrapper class.
Wrapper classes permits the creation of an object with the same type of a primitive type but with added methods and constants.
```java
WrapperClass objectName = new WrapperClass(primitiveValue); //decalration
WrapperClass objectName = new WrapperClass(primitiveValue); //declaration
WrapperClass objectName = primitiveValue; //shortened declaration
@ -182,19 +182,19 @@ int i = integer.parseInt(string);
```java
string.equals(otherString); // returns TRUE if the strings are equal
srting.equalsIgnoreCase(otherString); // returns TRUE if the strings are equals ignoring the case
string.charAt(index); // returns the character at positon INDEX
string.equalsIgnoreCase(otherString); // returns TRUE if the strings are equals ignoring the case
string.charAt(index); // returns the character at position INDEX
string.startsWith(otherString); // returns TRUE if string starts with otherString
string.endsWith(otherString) // returns TRUE if string ends with otherString
string.concat(otherString); // concatenation of two strings
string.indexOf(otherString); // returns index of the first occurrence of othre string
string.lastIndexOf(otherString); // returns index of the last occurrence of othre string
string.indexOf(otherString); // returns index of the first occurrence of other string
string.lastIndexOf(otherString); // returns index of the last occurrence of other string
string.length(); // returns the length of the string
string.toLowerCase(); // transform the string in uppercase characters
string.toUpperCase(); // transform the string in lowercase characters
string.repalce(character, newCharacter); // substitutes character with newCharacter
string.replaceAll(regex, replacecment);
string.substring(start, end); // returns a substring starting as START and ending at END (incluced)
string.replace(character, newCharacter); // substitutes character with newCharacter
string.replaceAll(regex, replacement);
string.substring(start, end); // returns a substring starting as START and ending at END (included)
string.trim(); // removes spaces before and after the string
string.Split(delimiter); // return a String[] generated by splitting string at the occurrence of delimiter
string.compareTo(otherString);
@ -207,7 +207,7 @@ string.compareTo(otherString);
- `1` if `otherString` precedes `string`
`compareTo()` compares the lexicographic order (based on UNICODE).
To compare in alphabetical order voth strings must have the same case.
To compare in alphabetical order both strings must have the same case.
### Mathematical Operations
@ -280,7 +280,7 @@ a `^` b | bitwise **XOR**
a `<<` b | bitwise left shift
a `>>` b | bitwise right shift
### Compound Assignement Operators
### Compound Assignment Operators
operator | operation
-----------|----------
@ -298,8 +298,8 @@ a `>>=` b | a = a >> b
### Operator Precedence
1. unary operators `++` , `--`, `!`
2. binary arithmetic opeartors `*`, `/`, `%`
3. binary arithmetic opeartors `+`, `-`
2. binary arithmetic operators `*`, `/`, `%`
3. binary arithmetic operators `+`, `-`
4. boolean operators `<`, `>` , `<=`, `>=`
5. boolean operators `==`, `!=`
6. bitwise operator `&`
@ -414,8 +414,8 @@ The iterator declared in the for is a local variable and can be used only in the
### Assertion Checks
If the asertion check is enabled (`java -ebableassetrions programName`) the execution of the algorithm is terminated if an assertion fails.
Asseretions can be used to check if a variable has a wanted value in a precise point in the code (Sanity Check).
If the assertion check is enabled (`java -ebableassetrions programName`) the execution of the algorithm is terminated if an assertion fails.
Assertions can be used to check if a variable has a wanted value in a precise point in the code (Sanity Check).
```java
assert <booleanExpression>;
@ -451,7 +451,7 @@ ClassName.methodName(arguments); //if method is used outside its class
## Array
## Array Delcaration
## Array Declaration
```java
Type[] arrayName = new Type[dimension];
@ -468,10 +468,10 @@ Type[] arrayName;
arrayType = new Type[dimension];
```
## Array Creation by Initializzation
## Array Creation by Initialization
`Type[] arrayName = {value1, value2, ...}`
Array dimansion is determined by the number of values.
Array dimension is determined by the number of values.
### Arrays as method parameters
@ -517,7 +517,7 @@ Type[]...[] arrayName = new Type[dimension1]...[dimensionN];
Type arrayName[]...[] = new Type[dimension1]...[dimensionN];
```
### Multi-Dimensional Arrats as parameters
### Multi-Dimensional Arrays as parameters
```java
static Type methodName (Type[]...[] ArrayName) {
@ -538,7 +538,7 @@ static Type[]...[] methodName (parameters) {
### Array Length of multi-dimensional arrays
```java
array.length //row lenght
array.length //row length
array[rowIndex].length //column length
```
@ -557,15 +557,15 @@ static void viewTable (Type[][] matrix){
## Recursion Guidelines
The core of the recursion must be constituited by a *conditional instruction* that permits to handle the cases basend on the method argument.
*At laest one* of the alternatives must contain a recurive call to che mathod. The call must resolve recuced version of the task handled by the method.
*At leats one* of the alternatives must not contain a recursive call or it must produce a value that constituites a base case or an arrest value.
The core of the recursion must be constituted by a *conditional instruction* that permits to handle the cases based on the method argument.
*At least one* of the alternatives must contain a recursive call to che method. The call must resolve reduced version of the task handled by the method.
*At leats one* of the alternatives must not contain a recursive call or it must produce a value that constitutes a base case or an arrest value.
## Exception Handling
An **Exception** is an object used to signal an anomalous event.
**Checked Exceptions** must be handled in a catch meanwhile **Uncchecked Exceptions** do not need to be catched like `RuntimeException`.
Unchecked exceptions usually mean thathere is an error in the logic of the program that must be fixed.
**Checked Exceptions** must be handled in a catch meanwhile **Unchecked Exceptions** do not need to be cached like `RuntimeException`.
Unchecked exceptions usually mean that there is an error in the logic of the program that must be fixed.
### `Try-Catch-Finally`
@ -576,7 +576,7 @@ try {
//monitored code
} catch (SpecificException e) {
//in case of errors use this
} catch (SpecificException1 | SpecficException2 | ... | SpecificExceptionN e) {
} catch (SpecificException1 | SpecificException2 | ... | SpecificExceptionN e) {
//in case of errors use this
} catch (Exception e) {
//in case of error use this
@ -594,7 +594,7 @@ A `try-catch` construct can handle multiple exceptions at once. Every `catch` i
try (
//resource definition
){
//dangerious code
//dangerous code
} catch (Exception e) {
//in case of error use this
} finally {
@ -619,7 +619,7 @@ The `throws` keyword is used to indicate what exception Type may be thrown by a
`throws` is used together with a exception class. It's used to send the exception to the method caller.
```java
Type methodName(parameters) throws ExcpetionClass {
Type methodName(parameters) throws ExceptionClass {
if (condition) {
throw new SpecificException("error message");
}
@ -651,7 +651,7 @@ public class CustomException extends Exception {
### Access Modifiers
`public` variables, methoda, classes are usable outside of class of definition.
`public` variables, methods, classes are usable outside of class of definition.
`private` variables, methods, classes are *only* usable inside class of definition.
`protected` variables, methods, classes can be accessed *only* by defining class, it's descendants and the package.
`final` classes and methods cannot be extended or overridden.
@ -701,28 +701,28 @@ It's possible to use `this` to distinguish between instance and static variables
### Classes and Reference Addresses
A an instance of a class doesen't contain an object of that class but a memory address in whitch the object is memorized.
operations of assignement (`=`) and confront (`==`) act on the memory address and not on the values of the objects.
To confront object is necessary to define a `equals()` method that chacks if the values of the object attributes are equal.
A an instance of a class doesn't contain an object of that class but a memory address in which the object is memorized.
operations of assignment (`=`) and confront (`==`) act on the memory address and not on the values of the objects.
To confront object is necessary to define a `equals()` method that checks if the values of the object attributes are equal.
### Constructors
Constructrs are special methods that are invoked with the `new` operator when an object is instantiated.
Constructors are special methods that are invoked with the `new` operator when an object is instantiated.
Constructors assign the starting values of the object attributes.
If a constructor id defined Java doesen't create the default constructor.
If a constructor id defined Java doesn't create the default constructor.
```java
class ClassName (){
//attributes dclaration (aka instance variables)
//attributes declaration (aka instance variables)
//constuctor
//constructor
public ClassName(parameters){
this.attribute = value; //value is passed to the constructor at obj instantiation
}
public ClassName(parameters, otherParameters){
this(parameters); // invoke other consstructor for subset of parameters, must be FIRST INSTRUCTION
this(parameters); // invoke other constructor for subset of parameters, must be FIRST INSTRUCTION
this.attribute = value; // deal with the remaining parameters
}
}
@ -731,7 +731,7 @@ class ClassName (){
### Static Variables
`Type staticVariable = value;`
Statc variables are shared by all objects of a class and all static method can act upon them.
Static variables are shared by all objects of a class and all static method can act upon them.
Static variable do not belong to the class objects.
### Getters & Setter Methods
@ -760,7 +760,7 @@ Public String toString(){
### Static Methods in Classes
Static methods are used to effectuate operations not applied to objects.
Outside of the class of definition thay are invoked with ClassName.methodName()
Outside of the class of definition that are invoked with ClassName.methodName()
Static method **cannot** act on instance variables.
### Method Overloading
@ -778,14 +778,14 @@ Child class **must** implement a constructor that instantiates the parent (super
`super()` instantiates the superclass of the child class.
```java
class ChildClass extends PerentClass{
class ChildClass extends ParentClass{
public ChildClass(parentParameters, childParameters){
super(parentParameters); // if omitted super() is calles (parent's default constructor)
// assignement of child attributes
super(parentParameters); // if omitted super() is calls (parent's default constructor)
// assignments of child attributes
}
//calss overrides parent class (must have same name)
//calls overrides parent class (must have same name)
@Override
Type methodName(parameters){
//code here
@ -795,7 +795,7 @@ class ChildClass extends PerentClass{
}
```
An overridden method that returns a `ParentClass` can be overridden to return a `ChildClass`. This is the only case in which an overridden method can change the retured type.
An overridden method that returns a `ParentClass` can be overridden to return a `ChildClass`. This is the only case in which an overridden method can change the returned type.
An overridden method can change the access modifier as long as the new modifier is more "permissive".
A `ParentClass` type can contain a `ChildClass` object. This is useful for using collections and arrays of objects.
@ -805,17 +805,17 @@ ParentClass objectName = ChildClass(); // upcast
(ChildClass)ParentClassObject; // downcast
```
### Abstact Classes & Abstract Methods
### Abstract Classes & Abstract Methods
An Abstact Class is a particular class that contains an Abstact Method.
This type of class cannot be instantiated but is used leave the specific implementatio of some of it's methods to extending classes.
Abstact classes are marked by the `abstract` keyword.
An Abstract Class is a particular class that contains an Abstract Method.
This type of class cannot be instantiated but is used leave the specific implementation of some of it's methods to extending classes.
Abstract classes are marked by the `abstract` keyword.
An abstract method is a method witout imlementation.
An abstract method is a method without implementation.
The methods **must** be `public` and marked with the `abstract` keyword.
```java
//abstarct class
//abstract class
abstract class className{
//attributes here
//constructor here
@ -828,12 +828,12 @@ abstract class className{
### Interfaces
An Interface is a class with *only* abstact methods. An interface has more flexibility than an abstract class.
Interfaces are used to set requirements for child clases without specifing how to satisfy those requirements since it's methods will be implemented in child classes.
An Interface is a class with *only* abstract methods. An interface has more flexibility than an abstract class.
Interfaces are used to set requirements for child classes without specifying how to satisfy those requirements since it's methods will be implemented in child classes.
An Interface is marked by the `interface` keyword.
If an implementing class implements only `some` of the interface's mathod than the class **must be abstract**.
If an implementing class implements only `some` of the interface's method than the class **must be abstract**.
Interfaces' methods are always `abstract` and `public`, no need for the kyword.
Interfaces' methods are always `abstract` and `public`, no need for the keyword.
Interfaces' attributes are always `public static final`, no need for the keyword.
A class can implement *more than one* Interface.
@ -849,7 +849,7 @@ public interface InterfaceName{
public interface OtherInterface extends InterfaceName {
//attributes here
Type methodName(); // inherited from extended interface
Type otherMethod(); // defined in thes interface
Type otherMethod(); // defined in the interface
}
class ClassName implements Interface1, Interface2 {...}
@ -858,16 +858,16 @@ class ClassName implements Interface1, Interface2 {...}
Types of Interfaces:
- Normal (multiple methods)
- Single Abstract Method (`@FunctionalInterface`, used with *Lamda Expressions*)
- Single Abstract Method (`@FunctionalInterface`, used with *Lambda Expressions*)
- Marker (Empty, *no methods*)
Since Java 1.8 interfaces can implements also `static` methods.
### Enumerations
Enums are used to restrict the type of data to a set of the possible constatnt values.
Enums are used to restrict the type of data to a set of the possible constant values.
Enums are classes which constructor is private by default.
It's still possible to createa a custom constructor to add values.
It's still possible to create a custom constructor to add values.
```java
enum enumName {
@ -887,13 +887,13 @@ enum enumName {
private Type value;
Type enumName(Type paramenter) {
Type enumName(Type parameter) {
this.value = parameter;
}
//getters are allowed, the values is a constant --> no setters
public Type getValue(){
retrurn this.value;
return this.value;
}
}
@ -916,7 +916,7 @@ AnonymousClass objectName = new AnonymousClass(Type parameter, ...) {
### Cloning
```java
class ClassName implements Cloneable {
class ClassName implements Clonable {
}
```
@ -1012,13 +1012,13 @@ try{
}
// write on the file
outSteram.print("");
outSteram.println("");
outStream.print("");
outStream.println("");
outStream.close() // close stream and write buffer contents.
```
**Note**: writing operations do not write direcly on the file. The sent data is collected in a **buffer**. When the buffer is *full* the data is written in the file. This is called *buffering* and is used to spped up operations.
**Note**: writing operations do not write directly on the file. The sent data is collected in a **buffer**. When the buffer is *full* the data is written in the file. This is called *buffering* and is used to append up operations.
#### Reading from a file
@ -1047,31 +1047,31 @@ try {
// code here
}
// BuffredReader Methods
// BufferedReader Methods
public String readLine() throws IOException // return file line or null (file has ended)
public int read() throws IOException // return an integer representin a char or -1 (file has ended)
public int read() throws IOException // return an integer representing a char or -1 (file has ended)
public long skip(n) throws IOException // skip n characters
public void close() throws IOException // closes the stream
```
#### `File()` class
The File class is an abstraction of the file and it's path. The abstraction is independant from the OS.
The File class is an abstraction of the file and it's path. The abstraction is independent from the OS.
```java
File("path/to/file") // UNIX like path
File("path\\to\\file") // Windows path
file.canRead() // true if file is readeble
file.canRead() // true if file is readable
file.canWrite() // true if file is writable
file.delete() // true if file has been deleted
file.exists() // check if exist a file with the filename used in the constructor
file.getName() // returns the filename
file.getPath() // returns the file's path
file.lenghth() // file lenght in bytes
file.length() // file length in bytes
```
### Bynary Files
### Binary Files
#### Writing to a binary file
@ -1146,7 +1146,7 @@ Needed for a class to be *serializable*:
- all instance variables are serializable
- superclass, if exists, is serializable or has default constructor
An array is serializable if it's base type is a rerializable object.
An array is serializable if it's base type is a serializable object.
```java
SerializableObject[] array = (SerializableObject[])inStream.readObject(); // read returns Object, cast needed
@ -1158,7 +1158,7 @@ SerializableObject[] array = (SerializableObject[])inStream.readObject(); // re
Functional interfaces provide target types for *lambda expressions*.
General purpose `@functioanlInterfaces`:
General purpose `@functionalInterfaces`:
```java
// takes input, performs actions, return boolean
@ -1189,7 +1189,7 @@ In java a *stream* is a [Monad][1]. Monads allow the programmer to compose a seq
The features of Java stream are:
- A stream is not a data structure instead it takes input from the Collections, Arrays or I/O channels.
- Streams don’t change the original data structure, they only provide the result as per the pipelined methods.
- Streams don't change the original data structure, they only provide the result as per the pipelined methods.
- Each intermediate operation is lazily executed and returns a stream as a result, hence various intermediate operations can be pipelined. Terminal operations mark the end of the stream and return the result.
**Intermediate Operations**:

8
Java/Spring Framework/Spring Project Structure.md
View file

@ -25,7 +25,7 @@ server.port=server_port
Model of a table of the DB
```java
package <base_pakcage>.entities;
package <base_package>.entities;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
@ -106,7 +106,7 @@ public interface IEntityService {
In `EntityService.java`:
```java
package com.lamonacamarcello.libri.services;
package <base_package>.services;
import java.util.List;
@ -162,7 +162,7 @@ public class EntityService implements IEntityService {
REST API routes & endpoints to supply data as JSON.
```java
package com.lamonacamarcello.libri.integration;
package <base_package>.integration;
import java.util.List;
@ -178,7 +178,7 @@ import <base_package>.services.IEntityService;
@RequestMapping("/api") // controller route
public class EntityRestCtrl {
@Autowired // connection to service (obj created by spring as needed: Inverion Of Control)
@Autowired // connection to service (obj created by spring as needed: Inversion Of Control)
private IEntityService service;
@GetMapping("entities") // site route

6
JavaScript/AJAX.md
View file

@ -20,8 +20,8 @@ var request = new XMLHttpRequest();
request.addEventListener(event, function() {...});
request.open("HttpMethod", "path/to/api", true); // third parameter is asynchronicity (true = asynchronous)
reqest.setRequestHeader(key, value) // HTTP Request Headers
reqest.send()
request.setRequestHeader(key, value) // HTTP Request Headers
request.send()
```
To check the status use `XMLHttpRequest.status` and `XMLHttpRequest.statusText`.
@ -75,7 +75,7 @@ request.send();
### `XMLHttpRequest` Browser compatibility
Old versions of IE don’t implement XMLHttpRequest. You must use the ActiveXObject if XMLHttpRequest is not available
Old versions of IE don't implement XMLHttpRequest. You must use the ActiveXObject if XMLHttpRequest is not available
```js
var request =window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP');

12
JavaScript/DOM.md
View file

@ -26,7 +26,7 @@ var node = document.querySelector('css-selector');
var nodes = document.querySelectorAll('css-selector');
```
## Manupulating the DOM
## Manipulating the DOM
### Manipulating a node's attributes
@ -43,7 +43,7 @@ var node = document.getElementById('id');
node.className = 'new-class';
```
### Manipulating a node’s style
### Manipulating a node's style
It's possible to access and change the styles of a DOM nodes via the **style** property.
CSS property names with a `-` must be **camelCased** and number properties must have a unit.
@ -63,7 +63,7 @@ pageNode.style.backgroundColor = 'pink';
pageNode.style.paddingTop = '10px';
```
### Manipulating a node’s contents
### Manipulating a node's contents
Each DOM node has an `innerHTML` attribute. It contains the HTML of all its children.
@ -103,7 +103,7 @@ In `page.html`:
In `script.js`:
```js
var formNode = document.getEleementById("Identifier");
var formNode = document.getElementById("Identifier");
var value = formNode.value;
```
@ -123,7 +123,7 @@ domNode.insertBefore(childToInsert, domnode);
domNode.parentNode.insertBefore(childToInsert, nodeAfterChild);
// remove a node
domnNod.removeChild(childToRemove);
domNode.removeChild(childToRemove);
node.parentNode.removeChild(node);
```
@ -152,7 +152,7 @@ body.appendChild(newParagraph);
function Node(params) {
this.node = document.createElement("tag");
this.node.attrubute = value;
this.node.attribute = value;
// operations on the node

6
JavaScript/Events & Animation.md
View file

@ -20,8 +20,8 @@ var onEvent = function(event) { // parameter contains info on the triggered eve
// logic here
}
domNode.addEventListener(eventType, calledback);
domNode.renoveEventListener(eventType, callback);
domNode.addEventListener(eventType, callback);
domNode.removeEventListener(eventType, callback);
```
### Bubbling & Capturing
@ -44,7 +44,7 @@ let event = new CustomEvent(type, { detail: /* custom data */ }); // create eve
domNode.dispatchEvent(event); // launch the event
```
![Event Inheritace](../.images/javascript_event-inheritance.png)
![Event Inheritance](../.images/javascript_event-inheritance.png)
## Animation

86
JavaScript/JavaScript.md
View file

@ -24,7 +24,7 @@
* @author author's name
* purpose of file
*
* detailed explanantion of what the file does on multiple lines
* detailed explanation of what the file does on multiple lines
*/
```
@ -56,7 +56,7 @@ alert("message");
[var vs let vs const](https://www.freecodecamp.org/news/var-let-and-const-whats-the-difference/)
Variable names can only contain numbers, digits, underscores and $. Varieble names are camelCase.
Variable names can only contain numbers, digits, underscores and $. Variable names are camelCase.
`let`: Block-scoped; access to variable restricted to the nearest enclosing block.
`var`: Function-scoped
@ -66,8 +66,8 @@ Variable names can only contain numbers, digits, underscores and $. Varieble nam
### Scope
Variabled declared with `let` are in local to the code block in which are declared.
Variabled declared with `var` are local only if declared in a function.
Variable declared with `let` are in local to the code block in which are declared.
Variable declared with `var` are local only if declared in a function.
```js
function func(){
@ -121,9 +121,9 @@ let string$ = 'text';
let string_ = `text ${expression}`; //string interpolation (needs backticks)
string.length; // length of the string
let char = string.charAt(index); // extaraction of a single character by position
let char = string.charAt(index); // extraction of a single character by position
string[index]; // char extraction by property access
let index = strinf.indexOf(substring); // start index of substring in string
let index = string.indexOf(substring); // start index of substring in string
```
Property access is unpredictable:
@ -170,7 +170,7 @@ typeof x; //returns the type of the variable x as a string
typeof(x); //returns the type of the variable x as a string
```
The result of typeof null is "object". That’s wrong.
The result of typeof null is "object". That's wrong.
It is an officially recognized error in typeof, kept for compatibility. Of course, null is not an object.
It is a special value with a separate type of its own. So, again, this is an error in the language.
@ -179,12 +179,12 @@ It is a special value with a separate type of its own. So, again, this is an err
```javascript
String(value); //converts value to string
Number(value); //converst value to a number
Number(value); //converts value to a number
Number(undefined); //--> NaN
Number(null); //--> 0
Number(true); //--> 1
Number(false); //--> 0
Number(String); //Whitespaces from the start and end are removed. If the remaining string is empty, the result is 0. Otherwise, the number is “read” from the string. An error gives NaN.
Number(String); //Whitespace from the start and end is removed. If the remaining string is empty, the result is 0. Otherwise, the number is "read" from the string. An error gives NaN.
Boolean(value); //--> true
Boolean(0); //--> false
@ -211,8 +211,8 @@ Number("A") == NaN; //false ?!?
```js
2 + 'text'; //"2text", implicit conversion and concatenation
1 + "1"; //"11", implicit conversion and concatention
"1" + 1; //"11", implicit conversion and concatention
1 + "1"; //"11", implicit conversion and concatenation
"1" + 1; //"11", implicit conversion and concatenation
+"1"; //1, implicit conversion
+"text"; // NaN
1 == "1"; //true
@ -231,7 +231,7 @@ Number("A") == NaN; //false ?!?
| `new` a(...) | object creation |
| a `in` b | membership |
### Mathemetical Operators
### Mathematical Operators
| Operator | Operation |
| -------- | -------------- |
@ -247,9 +247,9 @@ Number("A") == NaN; //false ?!?
| Operator | Operation |
| ------------ | ----------------- |
| `--`variable | prefix decrement |
| `++`variable | prefix incremente |
| variable`--` | postfiz decrement |
| variable`++` | ostfix increment |
| `++`variable | prefix increment |
| variable`--` | postfix decrement |
| variable`++` | postfix increment |
### Logical Operators
@ -267,7 +267,7 @@ Number("A") == NaN; //false ?!?
| a `<=` b | less or equal to |
| a `>` b | greater than |
| a `>=` b | greater or equal to |
| a `==` b | equaltity |
| a `==` b | equality |
| a `!=` b | inequality |
| a `===` b | strict equality |
| a `!==` b | strict inequality |
@ -281,8 +281,8 @@ Number("A") == NaN; //false ?!?
| a `^` b | bitwise XOR |
| `~`a | bitwise NOT |
| a `<<` b | bitwise left shift |
| a `>>` b | bitwise rigth sigt |
| a `>>>` b | bitwise unsigned rigth shift |
| a `>>` b | bitwise right shift |
| a `>>>` b | bitwise unsigned right shift |
### Compound Operators
@ -364,19 +364,19 @@ do {
### For Loop
```javascript
// baseic for
// basic for
for (begin; condition; step) { }
for (var variable in iterable) { } // for/in statement loops through the properties of an object
for (let variable in iterable) { } // inistatiate a new variable at each iteration
for (let variable in iterable) { } // instantiate a new variable at each iteration
// for/of statement loops through the values of an iterable objects
// for/of lets you loop over data structures that are iterable such as Arrays, Strings, Maps, NodeLists, and more.
for (var variable of iterable) { }
for (let variable of iterable) { } // inistatiate a new variable at each iteration
for (let variable of iterable) { } // instantiate a new variable at each iteration
// foreach (similar to for..of)
itearble.forEach(() => { /* statements */ });
iterable.forEach(() => { /* statements */ });
```
### Break & Continue statements
@ -385,11 +385,11 @@ itearble.forEach(() => { /* statements */ });
`continue;` skip to next loop cycle.
```javascript
labelname: for(begin; condition; step) {
label: for(begin; condition; step) {
//code here
}
break labelname; //breaks labelled loop and nested loops inside it
break label; //breaks labelled loop and nested loops inside it
```
## Arrays
@ -405,9 +405,9 @@ array[index] = item; // change or add item by index
array.push(item); //add item to array
array.pop(); // remove and return last item
array.join("separator"); // constuct a string from the items of the array, sepatated by SEPARATOR
array.join("separator"); // construct a string from the items of the array, separated by SEPARATOR
array.find(item => condition); // returns the value of the first element in the provided array that satisfies the provided testing function
array.fill(value, start, end); // filla an array with the passed value
array.fill(value, start, end); // fills an array with the passed value
// https://stackoverflow.com/a/37601776
@ -438,7 +438,7 @@ let array1 = [ 1, 2, 3, 4, 5, 6 ];
let array2 = [ 7, 8, 9, 10 ];
let copy = [ ...array1 ]; // shallow copy
let copyAndAdd = [ 0, ...array1, 7 ]; // insert all values in new array
let merge = [ ...array1, ...attay2 ]; // merge the arrays contents in new array
let merge = [ ...array1, ...array2 ]; // merge the arrays contents in new array
// objects
let obj = { prop1: value1, prop2: value2 };
@ -507,7 +507,7 @@ function functionName(parameter=default-value, ...args) {
```javascript
function functionName(parameters) {
if (parameter == undefined) {
paremeter = value;
parameter = value;
}
//code here
@ -542,7 +542,7 @@ let func = input => expression;
func(); // function call
// rerurn object literal
// return object literal
let func = (value) => ({property: value});
```
@ -550,7 +550,7 @@ let func = (value) => ({property: value});
An object is a collection of related data and/or functionality.
**Note**: It's not possible to transform a variable in an object simply by using the object assignement.
**Note**: It's not possible to transform a variable in an object simply by using the object assignment.
```js
let variable = value;
@ -567,7 +567,7 @@ let obj = {
method: function() {
// code here
this.properyName; // reference to object property inside the object
this.propertyName; // reference to object property inside the object
}
method; () => {
@ -575,7 +575,7 @@ let obj = {
}
};
// access to property (non existant porperties will return Undefined)
// access to property (non existant properties will return Undefined)
obj.property; // dot notation
obj["property"]; // array notation
@ -601,12 +601,12 @@ Notice that it has all the features you'd expect in a function, although it does
function Class(params) {
this.property = param;
this.method = function(parms) { /* code here */ }
this.method = function(params) { /* code here */ }
}
let obj = new Class(params); // object instantiation
let obj = new Object(); // cretaes empty object
let obj = new Object(); // creates empty object
let obj = new Object({
// JSON
});
@ -623,7 +623,7 @@ This is often referred to as a **prototype chain**, and explains why different o
If a method is implemented on an object (and not it's prototype) then only that object will heve that method and not all the ones that come from the same prototype.
```js
// constuctor function
// constructor function
function Obj(param1, ...) {
this.param1 = param1,
...
@ -712,10 +712,10 @@ let obj = {
let { var1, var2 } = obj; // extract values from object into variables
let { property: var1, property2 : var2 } = obj; // extract props in variables w/ specified names
let { property: var1, var2 = defalut_value } = obj; // use default values if object has less then expected props
let { property: var1, var2 = default_value } = obj; // use default values if object has less then expected props
```
### Array Deconstrions
### Array Deconstruction
```js
let array = [ 1, 2, 3, 4, 5, 6 ];
@ -726,10 +726,10 @@ let [first, , third, , seventh = "missing" ] = array; // extract specific value
```js
let object = {
// ojectt attributes
// object attributes
}
let json = JSON.stringify(object); // serialieze onbect in JSON
let json = JSON.stringify(object); // serialize object in JSON
let json = { /* JSON */ };
let object = JSON.parse(json); // deserialize to Object
@ -757,7 +757,7 @@ let timerId = setTimeout(function(arg1, ...){
clearTimeout(timerId) // cancel execution
// exemple of multiple consecutive schedules
// example of multiple consecutive schedules
let list = [1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", -1, -2, -3, -4, -5, -6, -7, -8, -9, -10]
function useTimeout(pos=0) {
@ -766,7 +766,7 @@ function useTimeout(pos=0) {
pos += 1; // update value for next call
if (pos < list.length) { // recursion exit condition
useTimeout(pos); // schedule next call with new walue
useTimeout(pos); // schedule next call with new value
}
}, 1_000, pos);
}
@ -777,7 +777,7 @@ useTimeout();
### `let` vs `var` with `setTimeout`
```js
// let instantitates a new variable for each iteration
// let instantiates a new variable for each iteration
for (let i = 0; i < 3; ++i) {
setTimeout(function() {
console.log(i);
@ -923,7 +923,7 @@ In `page.html`
In `module.js`:
```js
// exporting indivisual fratures
// exporting individual fractures
export default function() {} // one per module
export func = () => expression; // zero or more per module

10
JavaScript/React/React Router.md
View file

@ -1,10 +1,10 @@
# React Router
Popular routing library. Allows to specify a route through React components, declating which component is to be loaded for a given URL.
Popular routing library. Allows to specify a route through React components, declaring which component is to be loaded for a given URL.
Key Components:
- **Router**: wrap the app entrypoint, usually `BrowserRouter`
- **Router**: wrap the app entry-point, usually `BrowserRouter`
- **Route**: "Load this component for this URL"
- **Link**: react-managed anchors that won't post back to the browser
@ -74,7 +74,7 @@ import { Redirect } from "react-router-dom";
<Redirect from="/old-route" to="/new-route" />
{ condition && <Redirect to="/route" /> } // redirect if condition is true
// or redirect manipolating the history (always in props)
// or redirect manipulating the history (always in props)
props.history.push("/new-route");
```
@ -83,13 +83,13 @@ props.history.push("/new-route");
```js
import { Prompt } from "react-router-dom";
// displayes a prompt when the condition is true
// displays a prompt when the condition is true
<Prompt when={condition} message="prompt message" />
```
## Link
Clicks on a link created with React-Router will be captured by ract an all the routing will happen client side.
Clicks on a link created with React-Router will be captured by react an all the routing will happen client side.
```js
import { Link } from "react-router-dom";

12
JavaScript/React/React Tests.md
View file

@ -13,7 +13,7 @@ In `package.json`:
"test": "jest --watch" // watch re-runs test on save
},
"jest": {
// calls additional setups for enzyme, react tesing library, ...
// calls additional setups for enzyme, react testing library, ...
"setupFiles": [
"path/to/testSetup.js"
],
@ -64,16 +64,16 @@ In `Component.Snapshots.js`:
```js
import React from "react";
import rederer from "react-test-renderer";
import renderer from "react-test-renderer";
import Component from "./path/to/Component";
// import mock data if necessary
it("test descrtiption", () => {
it("test description", () => {
// renders the DOM tree of the component
const tree = renderer.create(<Component funcProp={jest.fn() /* mock function */} /* component props */ />);
// save a snaphot of the component at this point in time ( in __snaphsots__ folder)
// save a snapshot of the component at this point in time ( in __snapshots__ folder)
// in future test it will be checked to avoid regressions
// can be updated during jest --watch pressing "u"
expect(tree).matchSnapshot();
@ -89,7 +89,7 @@ it("test descrtiption", () => {
```js
// testSetup.js
import { configure } from "enzyme";
import Adapter from "enzyme-adapert-react-<version>";
import Adapter from "enzyme-adapter-react-<version>";
configure({ adapter: new Adapter() });
```
@ -128,7 +128,7 @@ it("test description", () => {
});
// mount rendering test
if("test descriotion" () => {
if("test description" () => {
const dom = mount(
<WrapperComponent>
<Component /* props *//>

16
JavaScript/React/React.md
View file

@ -2,7 +2,7 @@
## Components
Thera are two types of react components:
There are two types of react components:
- Function Components
- Class Components
@ -29,7 +29,7 @@ class Component extends React.Component {
Every components has two inputs: *props* and *state*. The props input is explicit while the state is implicit. State is used to determine the chages. Within the component state can be changed while the props object represent fixed values.
JSX syntax can resable HTML bat gets converted to pure JavaScript before being sent to the browser:
JSX syntax can reusable HTML bat gets converted to pure JavaScript before being sent to the browser:
```js
// JSX
@ -45,7 +45,7 @@ const element = React.createElement(
);
```
### App Entrypoint
### App Entry-point
```js
ReactDOM.render(
@ -60,7 +60,7 @@ ReactDOM.render(
### Dynamic Expressions
```js
<tag>{expression}</tag> // expression is evalueted an it's result is displayed
<tag>{expression}</tag> // expression is evaluated an it's result is displayed
<tag onEvent={funcReference}>{expression}</tag>
<tag onEvent={() => func(args)}>{expression}</tag>
```
@ -69,7 +69,7 @@ ReactDOM.render(
```js
<Component propName={value} /> // pass a value the component
<Component propName={funcreference} /> // pass a function to the component
<Component propName={funcReference} /> // pass a function to the component
function Component(props) {
// use props with {props.propName}
@ -135,7 +135,7 @@ class Button extends React.Component {
}
```
### Nesting Compnents
### Nesting Components
```js
import { useState } from "react";
@ -225,7 +225,7 @@ const [state, setState] = useState(default);
### `useEffect`
Hook used to trigger an action on each reder of the component or when one of the watched items changes.
Hook used to trigger an action on each render of the component or when one of the watched items changes.
```js
@ -240,7 +240,7 @@ useEffect(() => {
```js
// hook definitions
const useCutomHook = () => {
const useCustomHook = () => {
// eventual state definitions
// eventual function definitions

12
JavaScript/React/Redux Tests.md
View file

@ -2,10 +2,10 @@
## Tests for Connected Components
Connected components are warpped in a call to `connect`. Way of solving the problem:
Connected components are wrapped in a call to `connect`. Way of solving the problem:
- Wrap component with `<Provider>`. Added benefit: new store dedicated to tests.
- Add named export for unconncted component.
- Add named export for unconnected component.
In `Component.js`:
@ -38,8 +38,8 @@ function testHelper(args) {
it("test description", () => {
const dom = testHelper();
// simulate page interation
dom.find("selctor").simulate("<event>");
// simulate page iteration
dom.find("selector").simulate("<event>");
// find changed component
// test expected behaviour of component
@ -91,7 +91,7 @@ import initialState from "path/to/initialState";
import * as actions from "path/to/actionCreators";
it("test description", () => {
const store = createStore(toorReducer, initialState);
const store = createStore(storeReducer, initialState);
const expectedState = /* state after the update */
@ -126,7 +126,7 @@ import * as actions from "path/to/actionCreators";
describe("Async Actions", () => {
afterEach(() => {
fetchMock.restore(); // init fecth mock for each test
fetchMock.restore(); // init fetch mock for each test
});
it("test description", () => {

16
JavaScript/React/Redux.md
View file

@ -57,7 +57,7 @@ export function configStore(initialState) {
replaceReducer(newReducer); // replace an existing reducer, useful for Hot Reload
store.dispatch(action); // trigger a state change based on an action
store.subscribe(listener);
store.getState(); // retireve current state
store.getState(); // retrieve current state
```
### Reducers
@ -106,7 +106,7 @@ Container Components:
- Subscribe to Redux State
- Dispatch Redux actions
Presentaional Components:
Presentational Components:
- Focus on how things look
- Unaware of Redux
@ -145,23 +145,23 @@ import { increment, decrement, reset } from './actionCreators';
// const Component = ...
// specifies which state is passed to the component (called on satte change)
// specifies which state is passed to the component (called on state change)
const mapStateToProps = (state, ownProps /* optional */) => {
// structure of the props passsed to the component
// structure of the props passed to the component
return { propName: state.property };
};
// specifies the action passed to a component (the key is the name that the prop will have )
const mapDispatchToProps = { actionCreator: actionCreator };
// or
function mapDispathToProps(dispatch) {
function mapDispatchToProps(dispatch) {
return {
// wrap action creators
actionCreator: (args) => dispatch(actionCreator(args))
};
}
// or
function mapDispathToProps(dispatch) {
function mapDispatchToProps(dispatch) {
return {
actionCreator: bindActionCreators(actionCreator, dispatch),
actions: bindActionCreators(allActionCreators, dispatch)
@ -177,7 +177,7 @@ export default connect(mapStateToProps, mapDispatchToProps)(Component);
**Note**: Redux middleware runs *after* and action and *before* it's reducer.
Redux-Thunk allows to retrurn functions instead of objects from action creators.
Redux-Thunk allows to return functions instead of objects from action creators.
A "thunk" is a function that wraps an expression to delay it's evaluation.
In `configStore.js`:
@ -199,7 +199,7 @@ function configStore(initialState) {
```
```js
// usally action on async func success
// usually action on async func success
function actionCreator(arg) {
return { type: TYPE, data: arg };
}

6
JavaScript/Svelte/Svelte.md
View file

@ -10,7 +10,7 @@ node scripts/setupTypeScript.js
npm init vite@latest
```
## App Entrypoint
## App Entry-point
```js
import App from "./App.svelte"; // import the component
@ -74,7 +74,7 @@ export default app;
// markup here
{/each}
{#each array as item (key)} // usse key to determine changes
{#each array as item (key)} // use key to determine changes
// markup here
{/each}
```
@ -139,7 +139,7 @@ For these, Svelte has reactive declarations. They look like this:
```js
let count = 0;
$: double = count * 2; // recaclulatd when count changes
$: double = count * 2; // recalculated when count changes
// or
$: { }
$: <expression>

8
JavaScript/jQuery.md
View file

@ -90,9 +90,9 @@ $('a').css({'color': 'purple'});
### Create, Store, Manipulate and inject
```js
let paragraph = $('<p class="intro">Welcome<p>'); // creat and store element
let paragraph = $('<p class="intro">Welcome<p>'); // create and store element
paragraph.css('propery', 'value'); // manipulate element
paragraph.css('property', 'value'); // manipulate element
$("body").append(paragraph); // inject in DOM
```
@ -148,7 +148,7 @@ In the HTML, add a `<script>` ag that hotlinks to the CDN or source file:
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery-validate/1.17.0/jquery.validate.min.js"><script>
```
In the JavaScript call the jQuery puging on the DOM:
In the JavaScript call the jQuery plugin on the DOM:
```js
$("form").validate();
@ -195,7 +195,7 @@ banner.css('color', 'red')
### DOM Readiness
DOM manipulation and event binding doesn’t work if the `<script>` is in the `<head>`
DOM manipulation and event binding doesn't work if the `<script>` is in the `<head>`
```js
$(document).ready(function() {

10
Kotlin/kotlin.md
View file

@ -1,6 +1,6 @@
# Kotlin Cheat Sheet
## Pakage & Imports
## Package & Imports
```kotlin
package com.app.uniqueID
@ -21,13 +21,13 @@ val CONSTANT_NAME: Type = value //constant declaration
### Nullable Variables
For a variable to hold a null value, it must be of a nullable type.
Nulalble types are specified suffixing `?` to the variable type.
Nullable types are specified suffixing `?` to the variable type.
```kotlin
var nullableVariable: Type? = null
nullableVariable?.method() //correct way to use
//if var is null dont execute method() and return null
//if var is null don't execute method() and return null
nullablevariavle!!.method() //unsafe way
//!! -> ignore that var can be null
@ -81,7 +81,7 @@ when (variable){
//instead of chain of if-else
when {
condition -> value
condirion -> value
condition -> value
else -> value
}
```
@ -158,7 +158,7 @@ fun functionName(parameter: Type, function: (Type) -> Type): Type {
```kotlin
//primary constructor
class ClassName(private var attrivute: Type) {
class ClassName(private var attribute: Type) {
}

6
Markdown.md
View file

@ -10,7 +10,7 @@ Heading 2
---------
# Heading 1
## Headding 2
## Heading 2
### Heading 3
```
@ -20,7 +20,7 @@ Heading 2
*Italic* _Italic_
**Bold** __Bold__
~GitHub's striketrough~
~GitHub's strike-trough~
```
## Links & Images
@ -74,6 +74,6 @@ Heading 2
```markdown
| column label | column label | column label |
|:-------------|:------------:|--------------:|
| left-aligned | centered | right-alinged |
| left-aligned | centered | right-aligned |
| row contents | row contents | row contents |
```

2
Node.js/Node.js.md
View file

@ -1,6 +1,6 @@
# Node.js
Asyncronous JavaScript Engine
Asynchronous JavaScript Engine
## Syllabus

4
Node.js/Standard Packages/events.md
View file

@ -14,12 +14,12 @@ class CustomEmitter extends EventEmitter {} ;
const customEmitterObj = new CustomEmitter();
// add event listener
cusomEmitterObj.on("event", (e) => {
customEmitterObj.on("event", (e) => {
// e contains event object
})
// single-use event listener (execute and remove listener)
cusomEmitterObj.once("event", (e) => {
customEmitterObj.once("event", (e) => {
// e contains event object
})

4
Node.js/Standard Packages/fs.md
View file

@ -1,6 +1,6 @@
# fs (FIle System) Module
Async versions can acces file at the same time which can lead to conflicts in operations, erros can be handled in callback.
Async versions can access file at the same time which can lead to conflicts in operations, errors can be handled in callback.
Sync versions cannot interfere with each other, errors cause exceptions, handle in try-catch.
## Files
@ -71,7 +71,7 @@ fs.rmdirSync(path, recursive=false;
### Reading Directory Contents
```js
// read directrory contents
// read directory contents
fs.readdir(path, (err, files) => {}); // files is string[]
fs.readdir(path, { withFileTypes: true }, (err, files) => {}); // files is Dirent[]
fs.readdirSync(path); // returns string[] of files/directories

6
Node.js/Standard Packages/http(s).md
View file

@ -1,6 +1,6 @@
# HTTP(S) Module
## HTTTP(S) IncomingMessage (request)
## HTTPS(S) IncomingMessage (request)
### Making a request
@ -17,7 +17,7 @@ https.request(
).end();
```
### Reqest Methods & Properties
### Request Methods & Properties
```js
IncomingMessage.headers
@ -26,7 +26,7 @@ IncomingMessage.statusMessage
IncomingMessage.url
```
## HTTTP(S) ServerResponse (response)
## HTTPS(S) ServerResponse (response)
### Response Methods & Properties

2
Node.js/Standard Packages/os.md
View file

@ -16,5 +16,5 @@ os.homedir(); // CUrrent user home directory
os.hostname(); // PC Name
os.cpus(); // Array of CPU info
os.networkInterfaces(); // Array of Network Interfacecs info
os.networkInterfaces(); // Array of Network Interfaces info
```

2
Node.js/Standard Packages/process.md
View file

@ -15,7 +15,7 @@ process.arch // processor architecture
## Functions
```js
process.resourecUsage(); // resource usage for the current process
process.resourceUsage(); // resource usage for the current process
process.memoryUsage(); // memory usage of the Node.js process measured in bytes
process.exit(code); // terminate the process synchronously with an exit status of code
```

6
PHP/Composer & Autoloading.md
View file

@ -13,13 +13,13 @@ function autoloader($class) {
# __DIR__ -> path of calling file
# $class -> className (hopefully same as file)
# if class is in namesapce $class -> Namespace\className (hopefully folders mirror Namespace)
# if class is in namespace $class -> Namespace\className (hopefully folders mirror Namespace)
$class = str_replace("\\", DIRECTORY_SEPARATOR, $class); # avoid linux path separator issues
$fileName = sprintf("%s\\path\\%s.php", __DIR__, $class);
# or
$filename = sprintf("%s\\%s.php", __DIR__, $class); # if class is in namespaace
$filename = sprintf("%s\\%s.php", __DIR__, $class); # if class is in namespace
if (file_exists($fileName)) {
include $fileName;
@ -41,7 +41,7 @@ require "autoload.php";
### Multiple Autoloading
It's possible to resister multiple autoloading functions by calling `spl_autoloaad_register()` multiple times.
It's possible to resister multiple autoloading functions by calling `spl_autoload_register()` multiple times.
```php
# prepend adds the function at the start of the queue

14
PHP/Database.md
View file

@ -23,7 +23,7 @@ try {
### Queries
To execute a query it's necessaty to "prepare it" with *parameters*.
To execute a query it's necessary to "prepare it" with *parameters*.
```php
# literal string with markers
@ -34,9 +34,9 @@ WHERE field <operator> :marker'
$stmt = $pdo->prepare($sql, $options_array); # returns PDOStatement, used to execute the query
$stmt->execute([ ':marker' => value ]); # substitute marker with actual value
# fetchAll returns all mathces
$result = $stmt->fetchAll(); # result as associtive array AND numeric array (PDO::FETCH_BOTH)
$result = $stmt->fetchAll(PDO::FETCH_ASSOC); # result as associtive array
# fetchAll returns all matches
$result = $stmt->fetchAll(); # result as associative array AND numeric array (PDO::FETCH_BOTH)
$result = $stmt->fetchAll(PDO::FETCH_ASSOC); # result as associative array
$result = $stmt->fetchAll(PDO::FETCH_NUM); # result as array
$result = $stmt->fetchAll(PDO::FETCH_OBJ); # result as object of stdClass
$result = $stmt->fetchAll(PDO::FETCH_CLASS, ClassName::class); # result as object of a specific class
@ -90,13 +90,13 @@ $stmt->debugDumpParams(); # print the SQL query that has been sent to the datab
```php
$db = SQLite3("db_file.sqlite3"); // connection
$stmt = $db->prepare("SELECT fields FROM tables WHERE field <operator> :marker"); // preapre query
$stmt = $db->prepare("SELECT fields FROM tables WHERE field <operator> :marker"); // prepare query
$stmt->bindParam(":marker", $variable); // param binding
$result = $stmt->execute(); // retireve records
$result = $stmt->execute(); // retrieve records
$result->finalize(); // close result set, recommended calling before another execute()
$records = $results->fetchArray(SQLITE3_ASSOC); // extract records as array (flase if no results)
$records = $results->fetchArray(SQLITE3_ASSOC); // extract records as array (false if no results)
```
**NOTE**: Result set objects retrieved by calling `SQLite3Stmt::execute()` on the same statement object are not independent, but rather share the same underlying structure. Therefore it is recommended to call `SQLite3Result::finalize()`, before calling `SQLite3Stmt::execute()` on the same statement object again.

6
PHP/Dependecy Injection.md
View file

@ -14,13 +14,13 @@ class Foo
## Dependency Injection Container
The **Dependecy Injection Container** (DIC) allow to archive all the dependencies in a single `Container` class. Some offer automatic resolution of the dependecies.
The **Dependency Injection Container** (DIC) allow to archive all the dependencies in a single `Container` class. Some offer automatic resolution of the dependencies.
## [PHP-DI](https://php-di.org/)
The dependency injection container for humans. Installation: `composer require php-di/php-di`
- **Autowire** functionality: the ability of the container to create and inject the dependecy automatically.
- **Autowire** functionality: the ability of the container to create and inject the dependency automatically.
- Use of [Reflection](https://www.php.net/manual/en/intro.reflection.php)
- Configuration of the container through annotations & PHP code.
@ -57,7 +57,7 @@ class Foo
// config.php
use Psr\Container\ContainerInterface;
// config "primitrive" dependencies (dependecy => construct & return)
// config "primitive" dependencies (dependency => construct & return)
return [
'dsn' => 'sqlite:db.sq3',
PDO::class => function(ContainerInterface $c) {

62
PHP/PHP.md
View file

@ -26,7 +26,7 @@ In `config.php`:
```php
//config.php
//store configuration options in associtive array
//store configuration options in associative array
return [
setting => value,
setting = value,
@ -34,7 +34,7 @@ return [
```
```php
$config = include "config.php"; // retireve config and store into variable
$config = include "config.php"; // retrieve config and store into variable
```
## Namespace
@ -42,7 +42,7 @@ $config = include "config.php"; // retireve config and store into variable
[PSR-4 Spec](https://www.php-fig.org/psr/psr-4/)
```php
namespace Foo\Bar\Baz; # set nemespace for all file contents, \ for nested namespaces
namespace Foo\Bar\Baz; # set namespace for all file contents, \ for nested namespaces
use <PHP_Class> # using a namespace hides standard php classes (WHY?!?)
@ -54,7 +54,7 @@ namespace Foo\Bar\Baz {
};
Foo\Bar\Baz\func(); # use function from Foo\Bar\Baz withous USE instruction
Foo\Bar\Baz\func(); # use function from Foo\Bar\Baz without USE instruction
use Foo\Bar\Baz\func; # import namespace
func(); # use function from Foo\Bar\Baz
@ -106,7 +106,7 @@ if (!function_exists('readline')) {
## Variables
```php
$varibleName = value; # weakly typed
$variableName = value; # weakly typed
echo gettype(&variable); # output type of variable
var_dump($var); # prints info of variable (bit dimension, type & value)
@ -159,7 +159,7 @@ $c = 7E-10; // 0.0000000007
## Strings
A string is a sequrnce of ASCII characters. In PHP a string is an array of charachters.
A string is a sequence of ASCII characters. In PHP a string is an array of characters.
### String Concatenation
@ -172,10 +172,10 @@ $string1 .= $string2; # method 2
```php
strlen($string); # returns the string length
strpos($string, 'substring'); # position of dubstring in string
substr($string, start, len); # ectract substring of len from position start
strtoupper($string); # transfrorm to uppercase
strtolower($string); # transform to lowerchase
strpos($string, 'substring'); # position of substring in string
substr($string, start, len); # extract substring of len from position start
strtoupper($string); # transform to uppercase
strtolower($string); # transform to lowercase
explode(delimiter, string); # return array of substrings
@ -205,8 +205,8 @@ Heterogeneous sequence of values.
$array = (sequence_of_items); # array declaration and valorization
$array = [sequence_of_items]; # array declaration and valorization
# index < 0 selecst items starting from the last
$array[index]; # accest to the items
# index < 0 selects items starting from the last
$array[index]; # access to the items
$array[index] = value; # array valorization (can add items)
$array[] = value; # value appending
@ -279,7 +279,7 @@ $italianDay["Mon"]; # evaluates to Lunedì
## Conditional Instructions
### Conditional Opeartors
### Conditional Operators
| Operator | Operation |
| ----------- | ------------------------ |
@ -299,13 +299,13 @@ With `==` a string evaluates to `0`.
### Logical Operators
| Operator | Example | Result |
| -------- | ----------- | ---------------------------------------------------- | --- | ------------------------------------ |
| -------- | ----------- | ---------------------------------------------------- |
| `and` | `$a and $b` | TRUE if both `$a` and `$b` are TRUE. |
| `or` | `$a or $b` | TRUE if either `$a` or `$b` is TRUE. |
| `xor` | `$a xor $b` | TRUE if either `$a` or `$b` is TRUE, but _not both_. |
| `not` | `!$a` | TRUE if `$a` is _not_ TRUE. |
| `and` | `$a && $b` | TRUE if both `$a` and `$b` are TRUE. |
| `or` | `$a | | $b` | TRUE if either `$a` or `$b` is TRUE. |
| `or` | `$a || $b` | TRUE if either `$a` or `$b` is TRUE. |
### Ternary Operator
@ -317,7 +317,7 @@ condition ?: result_if_false;
### NULL Coalesce
```php
$var1 = $var2 ?? value; # if variable == NULL assign value, othervise return value of $var2
$var1 = $var2 ?? value; # if variable == NULL assign value, otherwise return value of $var2
# equivalent to
$var1 = isset($var2) ? $var2 : value
@ -328,7 +328,7 @@ $var1 = isset($var2) ? $var2 : value
```php
$a <=> $b;
# equivalen to
# equivalent to
if $a > $b
return 1;
if $a == $b
@ -445,7 +445,7 @@ do {
[Function Docstring](https://make.wordpress.org/core/handbook/best-practices/inline-documentation-standards/php/)
Parameters with default values are optional in the function call and must be the last ones in the function declaration. Return type is optional if type checking is diasbled.
Parameters with default values are optional in the function call and must be the last ones in the function declaration. Return type is optional if type checking is disabled.
```php
declare(strict_types=1); # activates type checking
@ -516,7 +516,7 @@ function functionName (?type $parameter): ?Type
## Anonymous Functions (Closure)
```php
# declaration and assignement to variable
# declaration and assignment to variable
$var = function (type $parameter) {
# code here
};
@ -576,12 +576,12 @@ class ClassName
const CONSTANT = value; # public by default
public $attribute; # null by default if not assigned
public Type $attribute; # specifing the type is optional, it will be enforced if present
public Type $attribute; # specifying the type is optional, it will be enforced if present
# class constructor
public function __construct(value)
{
$this->attrivute = value
$this->attribute = value
}
public getAttribute(): Type
@ -650,7 +650,7 @@ class ClassName
### Inheritance
If a class is defind `final` it can't be extended.
If a class is defined `final` it can't be extended.
If a function is declared `final` it can't be overridden.
```php
@ -664,7 +664,7 @@ class Child extends Parent
### Abstract Class
Abstract calsses cannot be instantiated;
Abstract classes cannot be instantiated;
```php
abstract class ClassName
@ -701,7 +701,7 @@ class ClassName implements InterfaceName {
`Traits` allows the reutilization of code inside different classes without links of inheritance.
It can be used to mitigate the problem of _multiple inheritance_, which is absent in PHP.
In case of functions name conflic it's possible to use `insteadof` to specify which function to use. It's also possible to use an _alias_ to resolve the conflicts.
In case of functions name conflict it's possible to use `insteadof` to specify which function to use. It's also possible to use an _alias_ to resolve the conflicts.
```php
trait TraitName {
@ -729,7 +729,7 @@ $obj->method(new class implements Interface {
## Serialization & JSON
```php
$serialized = serialize($obj); # serailization
$serialized = serialize($obj); # serialization
$obj = unserialize($serialized); # de-serialization
$var = json_decode(string $json, bool $associative); # Takes a JSON encoded string and converts it into a PHP variable.ù
@ -752,7 +752,7 @@ file_get_contents(filename); // read whole file
```php
preg_match('/PATTERN/', string $subject, array $matches); # returns 1 if the pattern matches given subject, 0 if it does not, or FALSE if an error occurred
# $mathces[0] = whole matched string
# $matches[0] = whole matched string
# $matches[i] = i-th group of the regex
```
@ -805,7 +805,7 @@ Algorithms currently supported:
- **threads** (integer) - Number of threads to use for computing the Argon2 hash. Defaults to PASSWORD_ARGON2_DEFAULT_THREADS.
```php
password_hash($passwrd, $algorithm); # create a new password hash using a strong one-way hashing algorithm.
password_hash($password, $algorithm); # create a new password hash using a strong one-way hashing algorithm.
password_verify($password, $hash); # Verifies that a password matches a hash
```
@ -814,7 +814,7 @@ password_verify($password, $hash); # Verifies that a password matches a hash
Types of PHP errors:
- **Fatal Error**: stop the execution of the program.
- **Warning**: generataed at runtime, does not stop the execution (non-blocking).
- **Warning**: generated at runtime, does not stop the execution (non-blocking).
- **Notice**: informative errors or messages, non-blocking.
```php
@ -849,7 +849,7 @@ ini_set("error_log", "path\\error.log"); // set log file
```php
// generate E_USER_ errors
trigger_error("message"); // defaul type: E_USER_NOTICE
trigger_error("message"); // default type: E_USER_NOTICE
trigger_error("message", E_USER_<Type>);
trigger_error("Deprecated Function", E_USER_DEPRECATED);
@ -873,9 +873,9 @@ PHP offers the possibility to handle errors with the _exception model_.
```php
try {
// dangerous code
} catch(ExcpetionType1 | ExceptionType2 $e) {
} catch(ExceptionType1 | ExceptionType2 $e) {
printf("Errore: %s", $e->getMessage());
} catch(Excpetion $e) {
} catch(Exception $e) {
// handle or report exception
}

2
PHP/PSR-7.md
View file

@ -2,7 +2,7 @@
## [PSR-7](https://www.php-fig.org/psr/psr-7/)
Standard of the PHP Framework Interop Group that defines common interafces for handling HTTP messages.
Standard of the PHP Framework Interop Group that defines common interfaces for handling HTTP messages.
- `Psr\Http\Message\MessageInterface`
- `Psr\Http\Message\RequestInterface`

4
PHP/Simple_MVC/Simple_MVC.md
View file

@ -23,7 +23,7 @@ composer create-project ezimuel/simple-mvc
| |- route.php --> routing
|- public
| |- img
| |- index.php --> app entrypoint
| |- index.php --> app entry-point
|- src
| |- Model
| |- View --> Plates views
@ -33,7 +33,7 @@ composer create-project ezimuel/simple-mvc
| |- Controller
```
### `indedx.php`
### `index.php`
```php
<?php

10
PHP/Templates with Plates.md
View file

@ -4,7 +4,7 @@
To separate HTML code and PHP code it's possible to use **templates** with markers for variable substitution.
Variables are created in the PHP code and are passed to the template in the **rendering** phase.
The server transmitts only the `index.php` file to the user. The php file renders the templates as needed.
The server transmits only the `index.php` file to the user. The php file renders the templates as needed.
```html
<html>
@ -20,7 +20,7 @@ The server transmitts only the `index.php` file to the user. The php file render
## [Plates](https://platesphp.com/)
Plates is a templete engine for PHP. A templete engine permits to separate the PHP code (businnes logic) from the HTML pages.
Plates is a template engine for PHP. A template engine permits to separate the PHP code (business logic) from the HTML pages.
Installation through composer: `composer require league/plates`.
@ -51,14 +51,14 @@ echo $templates->render("template_name", [
</html>
```
Variables in the template are created through an associtve array `key => value`. The key (`"key"`) becomes a variable (`$key`) in the template.
Variables in the template are created through an associative array `key => value`. The key (`"key"`) becomes a variable (`$key`) in the template.
### Layout
It's possible to create a layout (a model) for a group of pages to make that identical save for the contents.
In a layout it's possible to create a section called **content** that identifies content that can be specified at runtime.
**NOTE**: Sinsce only the template has the data passed eventual loops have to be done there.
**NOTE**: Since only the template has the data passed eventual loops have to be done there.
```php
# index.php
@ -94,7 +94,7 @@ echo $template->render('template_name', [ "marker" => value, ... ]);
It's necessary to verify that the output is in the necessary format.
Plates offerts `$this->escape()` or `$this->e()` to validate the output.
Plates offers `$this->escape()` or `$this->e()` to validate the output.
In general the output validation allows to prevent [Cross-Site Scripting][owasp-xss] (XSS).
[owasp-xss]: https://owasp.org/www-community/attacks/xss/

22
PHP/Unit Testing.md
View file

@ -43,7 +43,7 @@ PHPUnit can be configured in a XML file called `phpunit.xml`:
### Test Structure
**PHPUnit** tests are grouped in classes suffixed with `Test`. Each class *extends* `PHPUnit\Framework\TestCase`.
A test is a method of a *test class* prefized with `test`.
A test is a method of a *test class* prefixed with `test`.
PHPUnit is executed from the command line with `vendor/bin/phpunit --colors`.
```php
@ -85,10 +85,10 @@ class FilterTest extends TestCase
- `assertFalse()`: verifies that the element is false
- `assertEmpty()`: verifies that the element is empty
- `assertEquals()`: verifies that the two elements are equal
- `assertGreaterThan()`: verifies that the element is greter than ...
- `assertGreaterThan()`: verifies that the element is greater than ...
- `assertContains()`: verifies that the element is contained in an array
- `assertInstanceOf()`: verifies that the element is an instance of a specific class
- `assertArrayHasKey(mixed $key, array $array)`: verify taht a sopecific key is in the array
- `assertArrayHasKey(mixed $key, array $array)`: verify that a specific key is in the array
### [PHPUnit Testing Exceptions](https://phpunit.readthedocs.io/en/9.3/writing-tests-for-phpunit.html#testing-exceptions)
@ -98,13 +98,13 @@ public function testAggiungiEsameException(string $esame)
$this->expectException(Exception::class);
$this->expectExceptionMessage("exception_message");
// execute code that sould throw an exception
// execute code that should throw an exception
}
// https://github.com/sebastianbergmann/phpunit/issues/2484#issuecomment-648822531
public function testExceptionNotTrown()
public function testExceptionNotThrown()
{
$exceptioWasTrown = false;
$exceptionWasThrown = false;
try
{
@ -112,10 +112,10 @@ public function testExceptionNotTrown()
}
catch (EsameException $e)
{
$exceptioWasTrown = true;
$exceptionWasThrown = true;
}
$this->assertFalse($exceptioWasTrown);
$this->assertFalse($exceptionWasThrown);
}
// same as
@ -168,7 +168,7 @@ class DataTest extends TestCase
$this->assertEquals($expected, $a + $b);
}
// test recieves array contents as input
// test receives array contents as input
public function provider()
{
// must return array of arrays
@ -178,7 +178,7 @@ class DataTest extends TestCase
];
}
// test recieves array of arrays as input
// test receives array of arrays as input
public function provideArrayOfArrays()
{
return [
@ -226,5 +226,5 @@ class UnitTest extends TestCase
### Code Coverage (needs [XDebug](https://xdebug.org/))
```ps1
vendor/bin/phpunit --coverage-text # code cverage analisys in the terminal
vendor/bin/phpunit --coverage-text # code coverage analysis in the terminal
```

18
PHP/Web.md
View file

@ -12,7 +12,7 @@ PHP -S <ip:post> file.php # redirect requests to single file
## HTTP Methods
Handling of HTTP requests happend using the following global variables:
Handling of HTTP requests happens using the following global variables:
- `$_SERVER`: info on request headers, version, URL path and method (dict)
- `$_GET`: parameters of get request (dict)
@ -54,7 +54,7 @@ if (! move_uploaded_file($_FILES['photo']['tmp_name'], $path)) {
exit();
}
echo'<h1>File succesfully sent</h1>';
echo'<h1>File successfully sent</h1>';
```
### `$_SERVER`
@ -80,8 +80,8 @@ $_SERVER["HTTP_USER_AGENT"];
All sites **must** have a page for the consensus about using cookies.
**Cookies** are HTTP headers used to memorize key-value info *on the client*. They are sent from the server to the client to keep track of info on the user that is visting the website.
When a client recieves a HTTP response that contains `Set-Cookie` headers it has to memorize that info and reuse them in future requests.
**Cookies** are HTTP headers used to memorize key-value info *on the client*. They are sent from the server to the client to keep track of info on the user that is visiting the website.
When a client receives a HTTP response that contains `Set-Cookie` headers it has to memorize that info and reuse them in future requests.
```http
Set-Cookie: <cookie-name>=<cookie-value>
@ -95,7 +95,7 @@ Set-Cookie: <cookie-name>=<cookie-value>; HttpOnly
Anyone can modify the contents of a cookie; for this reason cookies **must not contain** *personal or sensible info*.
When a clien has memorized a cookie, it is sent in successive HTTP requests through the `Cookie` header.
When a client has memorized a cookie, it is sent in successive HTTP requests through the `Cookie` header.
```http
Cookie: <cookie-name>=<cookie-value>
@ -114,7 +114,7 @@ string $name,
[ bool $httponly = false ] // accessible only through http (no js, ...)
)
// examle: memorize user-id 112 with 24h expiry for site example.com
// example: memorize user-id 112 with 24h expiry for site example.com
setcookie ("User-id", "112", time() + 3600*24, "/", "example.com");
// check if a cookie exists
@ -123,12 +123,12 @@ if(isset($_COOKIE["cookie_name"])) {}
### [$_SESSION](https://www.php.net/manual/en/ref.session.php)
**Sessions** are info memorized *on the server* assoiciated to the client that makes an HTTP request.
**Sessions** are info memorized *on the server* associated to the client that makes an HTTP request.
PHP generates a cookie named `PHPSESSID` containing a *session identifier* and an *hash* generated from `IP + timestamp + pseudo-random number`.
To use the session it's necesary to recall the function `session_start()` at the beginning of a PHP script that deals with sessions.
After starting the session information in be savend in the `$_SESSION` array.
To use the session it's necessary to recall the function `session_start()` at the beginning of a PHP script that deals with sessions.
After starting the session information in be saved in the `$_SESSION` array.
```php
$_SESSION["key"] = value; // save data in session file (serialized data)

4
PowerShell/Powershell Commands.md
View file

@ -17,8 +17,8 @@ New-Item -ItemType SymbolicLink -Path .\link -Target .\Notice.txt # create a sy
Move-Item -Path <source> -Destination <target> # move and/or rename files and folders
Copy-Item -Path <source> -Destination <target> # copy (and rename) files and folders
Test-Path "path" -PathType Container # check if the exising path exists and is a folder
Test-Path "path" -PathType Leaf # check if the exising path exists and is a file
Test-Path "path" -PathType Container # check if the existing path exists and is a folder
Test-Path "path" -PathType Leaf # check if the existing path exists and is a file
# start, list , kill processes
Start-Process -FilePath <file> # open a file with the default process/program

20
PowerShell/Powershell Scripting.md
View file

@ -47,7 +47,7 @@ $a, $b = $b, $a
# Interpolation
Write-Host "text $variable" # single quotes will not interpolate
Write-Host (<expresion>)
Write-Host (<expression>)
```
### Built-in Variables
@ -80,10 +80,10 @@ $List = @() # Empty List
$String = $List -join 'separator'
$List = $String -split 'separator'
# List comprhensions
# List comprehensions
$List = sequence | Where-Object {$_ command} # $_ is current object
$Dict = @{"a" = "apple"; "b" = "ball"} # Dict definition
$Dict["a"] = "acron" # Item update
$Dict["a"] = "acorn" # Item update
# Loop through keys
foreach ($k in $Dict.keys) {
@ -127,16 +127,16 @@ switch(variable) {
# syntax
switch [-regex|-wildcard|-exact][-casesensitive] (<value>)
{
"string"|number|variable|{ expression } { statementlist }
default { statementlist }
"string"|number|variable|{ expression } { statement_list }
default { statement_list }
}
# or
switch [-regex|-wildcard|-exact][-casesensitive] -file filename
{
"string"|number|variable|{ expression } { statementlist }
default { statementlist }
"string"|number|variable|{ expression } { statement_list }
default { statement_list }
}
```
@ -155,7 +155,7 @@ foreach (item in iterable) {
}
while (condition) {
# Code heer
# Code here
}
do {
@ -251,7 +251,7 @@ function Func {
```ps1
$args # array of passed arguments
$args[$index] # access to the argumnets
$args[$index] # access to the arguments
$args.count # number of arguments
```
@ -261,7 +261,7 @@ In `scripts.ps1`:
```ps1
param($param1, $param2, ...) # basic usage
param($param1, $param2=defvalue, ...) # with dafault values
param($param1, $param2=defvalue, ...) # with default values
param([Type] $param1, $param2, ...) # specify a type
param([Parameter(Mandatory)]$param1, $param2, ...) # setting a parameter as necessary

12
RegularExpressions.md
View file

@ -5,14 +5,14 @@
`\d` any digit (0-9)
`\D` any non digit character
`\s` whitespace (space, tab, new line)
`\S` any non whitespace charaters
`\w` any alphanumeric charater (a-z, A-Z)
`\S` any non whitespace characters
`\w` any alphanumeric character (a-z, A-Z)
`\W` any non alphanumeric character
`\b` whitespace surrounding words (only at row start or end)
`\B` whitespace surrounding words (not at row start or end)
`\A` search only at string start
`\Z` search only at string end
`.` any charaters but newline (CRLF, CR, LF)
`.` any characters but newline (CRLF, CR, LF)
## Quantifiers
@ -38,15 +38,15 @@ Adding `?` *after* the qualifier makes it perform the match in non-greedy or min
## Character classes
`[__]` one of the charaters in the class (`[ab]` --> a or b)
`[__]` one of the characters in the class (`[ab]` --> a or b)
`[__]{m , n}` consecutive characters in the class (`[aeiou]{2}` --> ae, ao, ...)
`[a-z]` sequence of lowercase characters
`[A-Z]` sequence of uppercase characters
`[a-zA-Z]` sequence of lowercase or uppercase characters
`[a-z][A-Z]` sequence of lowercase characters followed by sequence of uppercase charaters
`[a-z][A-Z]` sequence of lowercase characters followed by sequence of uppercase characters
`[^__]` anything but the elements of the class (include `\n` to avoid matching line endings)
`^`, `\`, `-` and `]` must be escaped to be used in clases: `[ \]\[\^\- ]`
`^`, `\`, `-` and `]` must be escaped to be used in classes: `[ \]\[\^\- ]`
## Groups

20
Rust/Cargo.md
View file

@ -7,18 +7,18 @@ cargo new project_name # creates project folder and basic files
cargo new --vcs=git project_name # init project as git repo
```
## Building, Runnning & Checking a project
## Building, Running & Checking a project
Inside the project directory:
```ps1
cargo build # build progect and download eventual needed dependencies
cargo build --release # build project for realease (build + optimisations)
cargo build # build project and download eventual needed dependencies
cargo build --release # build project for release (build + optimisations)
cargo run # executes the built executable
cargo check # verifies buildability without producing an executable
```
## Dependecies
## Dependencies
In `Cargo.toml`:
@ -29,7 +29,7 @@ crate_name = "<version_number>"
## Code Organization
Rust has a number of features that allow to manage the code’s organization, including which details are exposed, which details are private, and what names are in each scope in the programs.
Rust has a number of features that allow to manage the code's organization, including which details are exposed, which details are private, and what names are in each scope in the programs.
These features, sometimes collectively referred to as the module system, include:
@ -44,7 +44,7 @@ A crate is a binary or library. The crate root is a source file that the Rust co
A package is one or more crates that provide a set of functionality. A package contains a `Cargo.toml` file that describes how to build those crates.
Several rules determine what a package can contain. A package must contain `zero` or `one` **library crates** (`lib` ?), and no more.
It can contain as many `binary` crates as you’d like, but it must contain at least one crate (either library or binary).
It can contain as many `binary` crates as you'd like, but it must contain at least one crate (either library or binary).
If a package contains `src/main.rs` and `src/lib.rs`, it has two crates: a library and a binary, both with the same name as the package.
A package can have multiple binary crates by placing files in the `src/bin` directory: each file will be a separate binary crate.
@ -58,7 +58,7 @@ Likewise, Cargo knows that if the package directory contains `src/lib.rs`, the p
Modules allow to organize code within a crate into groups for readability and easy reuse. Modules also control the privacy of items, which is whether an item can be used by outside code (*public*) or is an internal implementation detail and not available for outside use (*private*).
Define a module by starting with the `mod` keyword and then specify the name of the moduleand place curly brackets around the body of the module.
Define a module by starting with the `mod` keyword and then specify the name of the module and place curly brackets around the body of the module.
Inside modules, it's possible to have other modules. Modules can also hold definitions for other items, such as structs, enums, constants, traits, or functions.
### Paths
@ -102,7 +102,7 @@ mod file_level_module; // define a module for the whole file (same name as file
```
It's possible to use `pub` to designate *structs* and *enums* as public, but there are a few extra details.
If `pub` is used before a struct definition, this makes the struct public, but the struct’s fields will still be private.
If `pub` is used before a struct definition, this makes the struct public, but the struct's fields will still be private.
It's possible make each field public or not on a case-by-case basis.
In contrast, if an enum is made public, all of its variants are then public.
@ -114,7 +114,7 @@ use <crate_name>::module; // import module (abs path, other crate)
use crate::module; // import module (abs path, same crate)
use self::module; // import module (rel path, same crate)
use <crate_name>::module as alias; // import module w/ aliass
use <crate_name>::module as alias; // import module w/ aliases
pub use <crate_name>::module; // re-exporting (import and make available to others)
use <crate_name>::module::{self, Item}; // import multiple paths
@ -136,7 +136,7 @@ src
```rs
// main.rs
mod module; // delcare module direcotry as a module
mod module; // declare module directory as a module
// mod.rs
pub mod sub_module; // declare sub_module file as a module

74
Rust/Rust.md
View file

@ -19,7 +19,7 @@ fn main() { //program entry point
### Result types
The `Result` types are **enumerations**, often referred to as *enums*. An enumeration is a type that can have a *fixed set of values*, and those values are called the enum’s **variants**.
The `Result` types are **enumerations**, often referred to as *enums*. An enumeration is a type that can have a *fixed set of values*, and those values are called the enum's **variants**.
For `Result`, the variants are `Ok` or `Err`.
The `Ok` variant indicates the operation was *successful*, and inside `Ok` is the successfully generated value.
@ -75,7 +75,7 @@ const CONSTANT_NAME: type = value; // constant must have the type annotation
It's possible declare a new variable with the *same name* as a previous variable, and the new variable *shadows* the previous variable.
By using let, it's possible to perform a few transformations on a value but have the variable be immutable after those transformations have been completed.
The other difference between *mut* and *shadowing* is that because we’re effectively creating a new variable when we use the let keyword again,
The other difference between *mut* and *shadowing* is that because we're effectively creating a new variable when we use the let keyword again,
we can change the type of the value but reuse the same name.
```rs
@ -99,8 +99,8 @@ let x: i32 = 11; // shadowing
### Floating-Point Types
Rust also has two primitive types for floating-point numbers, which are numbers with decimal points.
Rust’s floating-point types are `f32` and `f64`, which are 32 bits and 64 bits in size, respectively.
The default type is `f64` because on modern CPUs it’s roughly the same speed as `f32` but is capable of more precision.
Rust's floating-point types are `f32` and `f64`, which are 32 bits and 64 bits in size, respectively.
The default type is `f64` because on modern CPUs it's roughly the same speed as `f32` but is capable of more precision.
### Numeric Operation
@ -119,9 +119,9 @@ Booleans are one byte in size. The Boolean type in Rust is specified using `bool
### Character Types
Rust’s `char` type is the language’s most primitive alphabetic type.
Rust's `char` type is the language's most primitive alphabetic type.
Rust’s `char` type is four bytes in size and represents a Unicode Scalar Value: range from `U+0000` to `U+D7FF` and `U+E000` to `U+10FFFF` inclusive.
Rust's `char` type is four bytes in size and represents a Unicode Scalar Value: range from `U+0000` to `U+D7FF` and `U+E000` to `U+10FFFF` inclusive.
```rs
let c: char = 'C'; // SINGLE QUOTES
@ -144,7 +144,7 @@ Tuples have a *fixed length*: once declared, they cannot grow or shrink in size.
```rs
let tup: (i32, f64, u8) = (500, 6.4, 1);
let (x, y, z) = tup; // tuple deconstructionj (unpacking)
let (x, y, z) = tup; // tuple deconstruction (unpacking)
tup.0; // member access
```
@ -152,19 +152,19 @@ tup.0; // member access
### Array Types
Every element of an array must have the *same type*. Arrays in Rust have a fixed length, like tuples.
An array isn’t as flexible as the `vector` type, though. A vector is a similar collection type provided by the standard library that *is allowed to grow or shrink in size*.
An array isn't as flexible as the `vector` type, though. A vector is a similar collection type provided by the standard library that *is allowed to grow or shrink in size*.
```rs
let array = [0, 1, 2, 3, 4];
let array: [Type; length] = [...];
let array: [value; length]; // same as python's [value] * length
array[index] = value; // member acces and update
array[index] = value; // member access and update
```
### Slice Types
Slices allows to reference a contiguos sequence of elements in a collection rather than the whole collection. **Slices don't take ownership**.
Slices allows to reference a contiguous sequence of elements in a collection rather than the whole collection. **Slices don't take ownership**.
```rs
let s = String::from("string literal");
@ -183,7 +183,7 @@ Rust code uses *snake_case* as the conventional style for function and variable
Function definitions in Rust start with `fn` and have a set of parentheses after the function name.
The curly brackets tell the compiler where the function body begins and ends.
Rust doesn’t care where the functions are defined, only that they’re defined somewhere.
Rust doesn't care where the functions are defined, only that they're defined somewhere.
```rs
fn func(param: Type) { // parameters MUST have the Type annotation
@ -261,12 +261,12 @@ for i in (start..end) { // (start..stop) is like python's range(start, stop)
## Ownership
Ownership is Rust’s most unique feature, and it enables Rust to make memory safety guarantees without needing a garbage collector.
Ownership is Rust's most unique feature, and it enables Rust to make memory safety guarantees without needing a garbage collector.
All programs have to manage the way they use a computer’s memory while running.
All programs have to manage the way they use a computer's memory while running.
Some languages have garbage collection that constantly looks for no longer used memory as the program runs; in other languages, the programmer must explicitly allocate and free the memory.
Rust uses a third approach: memory is managed through a system of ownership with a set of rules that the compiler checks at compile time.
None of the ownership features slow down your program while it’s running.
None of the ownership features slow down your program while it's running.
### Stack & Heap
@ -284,11 +284,11 @@ Comparatively, allocating space on the heap requires more work, because the allo
Accessing data in the heap is slower than accessing data on the stack because you have to follow a pointer to get there. Contemporary processors are faster if they jump around less in memory.
Keeping track of what parts of code are using what data on the heap, minimizing the amount of duplicate data on the heap, and cleaning up unused data on the heap so you don’t run out of space are all problems that ownership addresses.
Keeping track of what parts of code are using what data on the heap, minimizing the amount of duplicate data on the heap, and cleaning up unused data on the heap so you don't run out of space are all problems that ownership addresses.
### Ownership Rules
- Each *value* in Rust has a variable that’s called its *owner*.
- Each *value* in Rust has a variable that's called its *owner*.
- There can only be one owner at a time.
- When the owner goes out of scope, the value will be dropped.
@ -297,13 +297,13 @@ Keeping track of what parts of code are using what data on the heap, minimizing
A "shallow copy" of a variable allocated on the heap (C#'s reference value) the original variable goes out of scope and only the "copy" remains.
A "deep copy" (`var.clone()`) makes a copy of the data in the new variable without make the original fall out of scope.
When a variable goes out of scope, Rust calls a special function for us. This function is called `drop`, and it’s where the code to return the memory is located.
When a variable goes out of scope, Rust calls a special function for us. This function is called `drop`, and it's where the code to return the memory is located.
Rust has a special annotation called the `Copy` trait that we can place on types that are stored on the stack.
If a type has the `Copy` trait, an older variable is still usable after assignment.
Rust won’t let us annotate a type with the `Copy` trait if the type, or any of its parts, has implemented the `Drop` trait.
If the type needs something special to happen when the value goes out of scope and we add the `Copy` annotation to that type, we’ll get a compile-time error.
Rust won't let us annotate a type with the `Copy` trait if the type, or any of its parts, has implemented the `Drop` trait.
If the type needs something special to happen when the value goes out of scope and we add the `Copy` annotation to that type, we'll get a compile-time error.
```rs
let s = String::new()
@ -323,7 +323,7 @@ fn main() {
let x = 5; // x comes into scope
makes_copy(x); // x would move into the function, but i32 is Copy, so it’s okay to still use x afterward
makes_copy(x); // x would move into the function, but i32 is Copy, so it's okay to still use x afterward
} // Here, x goes out of scope, then s. But because s's value was moved, nothing special happens.
@ -372,7 +372,7 @@ A data race is similar to a race condition and happens when these three behavior
- Two or more pointers access the same data at the same time.
- At least one of the pointers is being used to write to the data.
- There’s no mechanism being used to synchronize access to the data.
- There's no mechanism being used to synchronize access to the data.
```rs
fn borrow(var: &Type) { // &Type indicates that the var is a reference
@ -391,7 +391,7 @@ fn borrow2(var: &mut Type) {
A **struct**, or structure, is a custom data type that allows to name and package together multiple related values that make up a meaningful group.
To define a struct enter the keyword struct and name the entire struct.
A struct’s name should describe the significance of the pieces of data being grouped together.
A struct's name should describe the significance of the pieces of data being grouped together.
Then, inside curly brackets, define the names and types of the pieces of data, which we call *fields*.
```rs
@ -412,7 +412,7 @@ let mut var = Struct {
};
fn build_struct(param: Type, ...) -> Struct {
// the constructed struct is returned siince it's the last expression
// the constructed struct is returned since it's the last expression
Struct {
field: param,
...
@ -424,7 +424,7 @@ fn build_struct(param: Type, ...) -> Struct {
```rs
fn build_struct(field: Type, ...) -> Struct {
// the constructed struct is returned siince it's the last expression
// the constructed struct is returned since it's the last expression
Struct {
field, // shortened form since func param is named as the struct's field
...
@ -434,7 +434,7 @@ fn build_struct(field: Type, ...) -> Struct {
var.field = value; // member access
```
**Note**: the entire instance must be mutable; Rust doesn’t allow to mark only certain fields as mutable.
**Note**: the entire instance must be mutable; Rust doesn't allow to mark only certain fields as mutable.
### Struct Update Syntax
@ -462,7 +462,7 @@ struct Point(i32, i32, i32);
let origin = Point(0, 0, 0);
```
### Stuct Printing
### Struct Printing
```rs
#[derive(Debug)] // inherit the debug traits
@ -472,7 +472,7 @@ struct StructName
...
}
let s: Struct = { /* valorzation */};
let s: Struct = { /* valorization */};
printl!("{:?}", s) // debug output: { field: value, ... }
```
@ -490,8 +490,8 @@ impl Struct
fn method(&self, arg: Type) -> Type { }
}
let s: Struct = { /* valorzation */};
s.method(arg); // use struct mathod
let s: Struct = { /* valorization */};
s.method(arg); // use struct method
```
## Enums
@ -505,7 +505,7 @@ enum Enum
...
}
// value assigenement
// value assignment
let e: Enum = Enum::Variant2;
let e: Enum = Enum::Variant1(arg, ...); // variant w/ data
@ -518,9 +518,9 @@ impl Enum
### [Option enum](https://doc.rust-lang.org/std/option/enum.Option.htmls)
The `Option` type is used in many places because it encodes the very common scenario in which a value could be something or it could be nothing. Expressing this concept in terms of the type system means the compiler can check whether you’ve handled all the cases you should be handling; this functionality can prevent bugs that are extremely common in other programming languages.
The `Option` type is used in many places because it encodes the very common scenario in which a value could be something or it could be nothing. Expressing this concept in terms of the type system means the compiler can check whether you've handled all the cases you should be handling; this functionality can prevent bugs that are extremely common in other programming languages.
he `Option<T>` enum is so useful that it’s even included in the prelude; you don’t need to bring it into scope explicitly.
he `Option<T>` enum is so useful that it's even included in the prelude; you don't need to bring it into scope explicitly.
In addition, so are its variants: you can use `Some` and `None` directly without the `Option::` prefix.
```rs
@ -531,15 +531,15 @@ enum Option<T> {
}
```
*NOTE*: When `None` is used the type of `Option<T>` must be specified, because the compiler can’t infer the type that the `Some` variant will hold by looking only at a `None` value.
*NOTE*: When `None` is used the type of `Option<T>` must be specified, because the compiler can't infer the type that the `Some` variant will hold by looking only at a `None` value.
### Match Expression + Comparing
A **match expression** is made up of *arms*.
An arm consists of a *pattern* and the code that should be run if the value given to the beginning of the match expression fits that arm’s pattern.
Rust takes the value given to match and looks through each arm’s pattern in turn.
An arm consists of a *pattern* and the code that should be run if the value given to the beginning of the match expression fits that arm's pattern.
Rust takes the value given to match and looks through each arm's pattern in turn.
**NOTE**: `match` arms must be exaustive for compilation.
**NOTE**: `match` arms must be exhaustive for compilation.
```rs
enum Enum {
@ -575,7 +575,7 @@ v.push(item); // add elements to vector
// element access
v.get(index); // get method (returns Option<&T>)
&v[index]; // index synatx (returns reference, panic on index out of bounds)
&v[index]; // index syntax (returns reference, panic on index out of bounds)
// iterate over mutable references to each element in a mutable vector in order to make changes to all the elements
for i in mut &v {

38
Swift/Swift.md
View file

@ -11,7 +11,7 @@
```swift
#if DEBUG
// contents compilde only if in DEBUG build
// contents compiled only if in DEBUG build
#endif
```
@ -64,7 +64,7 @@ to make a string span multiple lines"""
var array = ["firstItem", "secondItem", ...]
var array = [Type()] // init empty homogeneous array
array[index] // value acces
array[index] // value access
array[index] = value // value update
array.append(item) // add item to the end
@ -106,7 +106,7 @@ var (var1, var2) = tuple // var1 = value1, var2 = value2
## Type Identifier
```swift
typealis Point = (Int, Int)
typealias Point = (Int, Int)
var origin: (0, 0)
```
@ -130,9 +130,9 @@ dict[key] = value // value update
| Syntax | Operation |
|---------------------|---------------------------------------------------------------------|
| x`.`m | accest to member `m` of object `x` ("." --> member access operator) |
| x`.`m | access to member `m` of object `x` ("." --> member access operator) |
| x`(...)` | method invocation ("()" --> method invocation operator) |
| x`[...]` | array access and indicizarion |
| x`[...]` | array access and indicization |
| `new` T(...) | object instantiation |
| `x!` | declare x as not nil |
@ -148,9 +148,9 @@ dict[key] = value // value update
| `--`x | pre-decrement |
| x`++` | post-increment |
| x`--` | post decrement |
| `(type)`x | explict casting |
| `(type)`x | explicit casting |
### Methematical Operators
### Mathematical Operators
| Operator | Operation |
| -------- | ----------------------------------------------------- |
@ -160,7 +160,7 @@ dict[key] = value // value update
| x `/` y | integer division, **always** returns an `int` |
| x `%` y | modulo, remainder |
| x `<<` y | left bit shift |
| x `>>` y | rigth bit shift |
| x `>>` y | right bit shift |
### Relational Operators
@ -186,7 +186,7 @@ dict[key] = value // value update
| x `??` y | evaluates to `y` only if `x` is `nil`, `x` otherwise | nil coalescing |
| x`?.`y | stop if `x == nil`, evaluate `x.y` otherwise | nil conditional |
### Assignement
### Assignment
| Operator | Operation |
|-----------|------------------------|
@ -289,7 +289,7 @@ func funcName(param: Type, ...) {
// code here
}
func funcName(param: Type = dafaultValue, ...) -> Type {
func funcName(param: Type = defaultValue, ...) -> Type {
//code here
return <expression>
}
@ -309,7 +309,7 @@ func funcMultipleParameters(param: Type) -> (retVal1: Type, retVal2: Type) {
}
var result = funcMultipleReturns(param: value)
result.retVal1 // acces to tuple components
result.retVal1 // access to tuple components
// argument labels (only first label can be omitted)
func funcWithLabels(_ param: Type, label param: Type, ...) -> Type { }
@ -323,7 +323,7 @@ func f(param: Type) -> Type {}
func g(f: (Type) -> Type) {} // (Type) -> Type are the passed func input and output types
```
### Functions Returniing Functions
### Functions Returning Functions
```swift
func f() -> ((Type) -> Type) {
@ -384,7 +384,7 @@ enum IntegerEnum: Int {
```swift
enum Rank: Int {
case ace = 1, two, three, four, five, six, seven, eigth, nine, ten
case ace = 1, two, three, four, five, six, seven, eight, nine, ten
case jack, queen, king
func getValue() -> String {
@ -429,9 +429,9 @@ struct StructName {
self.attribute = param // attribute valorization
}
// deinitializer (free memory containing obj?)
// de-initializer (free memory containing obj?)
deinit {
// empty the arrtibutes
// empty the attributes
}
// overloading
@ -464,9 +464,9 @@ class ClassName {
self.attribute = param // attribute valorization
}
// deinitializer (free memory containing obj?)
// de-initializer (free memory containing obj?)
deinit {
// empty the arrtibutes
// empty the attributes
}
// overloading
@ -479,7 +479,7 @@ var obj = ClassName() // obj instantiation
### Property Observers `willSet` & `didSet`
Do actions before/after modifing a property value.
Do actions before/after modifying a property value.
**NOTE**: `willSet` and `didSet` do not *set* the value of the property.
@ -497,7 +497,7 @@ class ClassName {
}
didSet {
// act after setting the propery value
// act after setting the property value
}
}
}

2
iOS/AppDelegate (XCode 11) .md
View file

@ -1,6 +1,6 @@
# AppDelegate
First loaded file. It prepares the app visualiation by calling the *scene* UI.
First loaded file. It prepares the app visualisation by calling the *scene* UI.
```swift
import UIKit

26
iOS/ContentView.md
View file

@ -4,17 +4,17 @@ A page of the app.
## Views, Functions & Variables
`@State` allows the view to respond to every change of the anotated variable. This variables get initialized by the view in which they belong and are not "recieved" from external objects.
`@State` allows the view to respond to every change of the annotated variable. This variables get initialized by the view in which they belong and are not "received" from external objects.
SwiftUI memorizes internally the value of the `@State` property and updates the view every time it changes.
`@Binding` is used for properties that are passed to the view from another. The recieveing view can read the binfing value, react to changes and modify it's value.
`@Binding` is used for properties that are passed to the view from another. The receiving view can read the binding value, react to changes and modify it's value.
`@Binding` variables are passed with the prefix `$`,
### Simple View
- Simplest view.
- Permits the visualization of simple UIs.
- Constituited by a body of type `View`
- Constituted by a body of type `View`
```swift
struct SimpleViewName: View {
@ -36,7 +36,7 @@ struct SimpleViewName: View {
### HStack, VStack, ZStack
Used to organize elements without dealing with constraints or forcing the visualization on devices wih differents screen sizes.
Used to organize elements without dealing with constraints or forcing the visualization on devices wih different screen sizes.
```swift
struct ContentView: View {
@ -54,8 +54,8 @@ struct ContentView: View {
### Table View
Most common view to present array contents, it automatically hendles the scrolling of the page with the *bounce* effect.
I can be inegrate d in a `NavigaionView` to handle a `DeailView` of a selectted item in the list.
Most common view to present array contents, it automatically handles the scrolling of the page with the *bounce* effect.
It can be integrated in a `NavigationView` to handle a `DetailView` of a selected item in the list.
The basic object that creates the table view is the `List()`. It's job is to create a "cell" for every element in the array.
The array can be filtered with a *search bar*.
@ -105,8 +105,8 @@ struct ContentView: View {
### Tab Bar View
This view handles a bar on the botom of the screen with links to simple or more comlpex views.
This is useful for designing pages that can be easely navigated by the user.
This view handles a bar on the bottom of the screen with links to simple or more complex views.
This is useful for designing pages that can be easily navigated by the user.
```swift
struct TabBarView: View {
@ -132,11 +132,11 @@ struct TabBarView: View {
The `TabBar` construction is made applying the `.tabItem{}` parameter to the object or page that the tab will link to.
It's possible to specify up to 5 `.tabItem{}` elements that will be displayed singularly in the `TabBar`.
Fron the 6th elemnet onwards, the first 4 elemens will appear normally, meanwhile the 5th will become a "more" element that will open a `TableView` with the list of the other `.tabItem{}` elements. This page permis to define which elements will be visible.
From the 6th element onwards, the first 4 elements will appear normally, meanwhile the 5th will become a "more" element that will open a `TableView` with the list of the other `.tabItem{}` elements. This page permission to define which elements will be visible.
It's possible to integrate the NavigationView in the TabBar in two ways:
- inserting it as a container for the whole `TabBar` (at the moment of the transistion to the detail page the `TabBar` will be hidden)
- inserting it as a container for the whole `TabBar` (at the moment of the transition to the detail page the `TabBar` will be hidden)
- inserting it as a container of a single `.tabItem{}` (the transition will happen inside the `TabBar` that will then remain visible)
## View Elements
@ -191,12 +191,12 @@ Button(action: { /* statements */ }) {
Common syle options:
- `padding()`: adds an internal padding to the object.
- `foregroundColor()`: defines the color of the text or containd object.
- `foregroundColor()`: defines the color of the text or contained object.
- `background()`: defines the background color.
- `font()`: sets font type, size, weight, ...
- `cornerRadius()`: modifies the angles of the containing box.
- `frame()`: sets a fixed size for the object.
- `resizable()`, `scaleToFill()`, `scaleToFit()`: habled the resizing of an object inside another.
- `resizable()`, `scaleToFill()`, `scaleToFit()`: enables the resizing of an object inside another.
- `clipShape()`: overlays a shape over the object
- `overlay()`: overlays an element over the object, more complex than clipShape
- `shadow()`: Sets the object's shadow
@ -255,7 +255,7 @@ Slider(value: $numVariable)
```swift
@State private var apiItems = [<struct>]()
// struct sould be Identifiable & Codable
// struct should be Identifiable & Codable
func loadData() {
guard let url = URL(string: "https://jsonplaceholder.typicode.com/todos")

2
iOS/SceneDelegate (XCode 11).md
View file

@ -31,7 +31,7 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
// Called as the scene is being released by the system.
// This occurs shortly after the scene enters the background, or when its session is discarded.
// Release any resources associated with this scene that can be re-created the next time the scene connects.
// The scene may re-connect later, as its session was not neccessarily discarded (see `application:didDiscardSceneSessions` instead).
// The scene may re-connect later, as its session was not necessarily discarded (see `application:didDiscardSceneSessions` instead).
}
func sceneDidBecomeActive(_ scene: UIScene) {