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feat(c): rewrite C++ notes as C notes
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2 changed files with 83 additions and 250 deletions
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@ -1,20 +1,13 @@
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# C/C++
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## Naming convention
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C++ element | Case
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-------------|------------
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class | PascalCase
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variable | camelCase
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method | camelCase
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## Library Import
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`#include <iostream>`
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C++ libs encapsulate C libs.
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A C library can be used with the traditional name `<lib.h>` or with the prefix _**c**_ and without `.h` as `<clib>`.
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```c
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#include <stdio.h> // search in current + system directories
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#include "lib.h" // search in current directory
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```
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### Special Operators
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## Special Operators
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Operator | Operator Name
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-----------|----------------------------------------------------
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@ -22,38 +15,29 @@ Operator | Operator Name
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`&` | address operator (returns a memory address)
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`*` | deferentiation operator (returns the pointed value)
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### Constant Declaration
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```cpp
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#define constant_name value
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const type constant_name = value;
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```
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### Console pausing before exit
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```cpp
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#include <cstdlib>
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system("pause");
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getchar(); // waits input from keyboard, if is last instruction will prevent closing console until satisfied
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```
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### Namespace definition
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## Namespace definition
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Can be omitted and replaced by namespace`::`
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`using namespace <namespace>;`
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### Main Function
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## Main Function
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```cpp
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int main() {
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//code here
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return 0;
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}
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```c
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int main(int argc, char *argv[]) { }
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```
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## Variables & Types
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### Constant Declaration
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```c
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#define constant_name value
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const type constant_name = value;
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```
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### Variable Declaration
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```cpp
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```c
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type var_name = value; //c-like initialization
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type var_name (value); //constructor initialization
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type var_name {value}; //uniform initialization
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@ -100,7 +84,7 @@ Example | Type
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`75ul` | unsigned long
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`75lu` | unsigned long
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### FLOATING POINT NUMERALS
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### Floating Point Numerals
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Example | Type
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------------|-------------
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@ -136,32 +120,21 @@ Escape Character | Character
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`\\` | backslash (\)
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`\0` | string termination character
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### Screen Output
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## Standard Input/Output
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```cpp
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cout << expression; // print line on screen (no automatic newline)
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cout << expression_1 << expression_2; // concatenation of outputs
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cout << expression << "\n"; // print line on screen
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cout << expression << endl; // print line on screen
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### Standard Output
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//Substitutes variable to format specifier
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```c
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#include <stdio.h>
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printf("text %<fmt_spec>", variable); // has problems, use PRINTF_S
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printf_s("text %<fmt_spec>", variable);
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```
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### Input
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```cpp
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#include <iostream>
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cin >> var; //space terminates value
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cin >> var_1 >> var_2;
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//if used after cin >> MUST clear buffer with cin.ignore(), cin.sync() or std::ws
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getline(stream, string, delimiter) //read input from stream (usually CIN) and store in in string, a different delimiter character can be set.
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### Standard Input
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```c
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#include <stdio.h>
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scanf("%<fmt_spec>", &variable); // has problems, use SCANF_S
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scanf_s("%<fmt_spec>", &variable); //return number of successfully accepted inputs
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```
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@ -184,37 +157,7 @@ Specifier | Specified Format
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`%s` | string
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`%p` | pointer address
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### CIN input validation
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```cpp
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if (cin.fail()) // if cin fails to get an input
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{
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cin.clear(); // reset cin status (modified by cin.fail() ?)
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cin.ignore(n, '\n'); //remove n characters from budder or until \n
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//error message here
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}
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if (!(cin >> var)) // if cin fails to get an input
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{
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cin.clear(); // reset cin status (modified by cin.fail() ?)
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cin.ignore(n, '\n'); //remove n characters from budder or until \n
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//error message here
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}
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```
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### Cout Format Specifier
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```cpp
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#include <iomanip>
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cout << stew(print_size) << setprecision(num_digits) << var; //usage
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setbase(base) //set numeric base [dec, hex, oct]
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setw(print_size) //set the total number of characters to display
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setprecision(num_digits) //sets the number of decimal digits to display
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setfill(character) //use character to fill space between words
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```
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## Operators
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### Arithmetic Operators
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@ -263,7 +206,7 @@ a `^` b, a `xor` b, | bitwise **XOR**
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a `<<` b | bitwise left shift
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a `>>` b | bitwise right shift
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### Compound Assignment O
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### Compound Assignment Operators
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Operator | Operation
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------------|------------
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@ -289,10 +232,13 @@ a `>>=` b | a = a >> b
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7. `||`
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8. `=`
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## Common Functions
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### Mathematical Functions
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```cpp
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```c
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#include <cmath>
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abs(x); // absolute value
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labs(x); //absolute value if x is long, result is long
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fabs(x); //absolute value if x i float, result is float
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@ -315,9 +261,9 @@ cosh(x); //hyperbolic cos(x)
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tanh(x); //hyperbolic tan(X)
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```
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### Character Classification
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### Character Functions
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```cpp
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```c
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isalnum(c); //true if c is alphanumeric
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isalpha(c); //true if c is a letter
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isdigit(c); //true if char is 0 1 2 3 4 5 6 7 8 9
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@ -330,61 +276,14 @@ isupper(c); //true if c is uppercase
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ispunct(c); //true if c is punctuation
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isspace(c); //true if c is SPACE
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isxdigit(c); //true if c is HEX DIGIT
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```
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### Character Functions
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```cpp
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#include <ctype.n>
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tolower(c); //transforms character in lowercase
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toupper(c); //transform character in uppercase
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```
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### Random Numbers Between max-min (int)
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```cpp
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#include <time>
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#include <stdlib.h>
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srand(time(NULL)); //initialize seed
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var = rand() //random number
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var = (rand() % max + 1) //random numbers between 0 & max
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var = (rand() % (max - min + 1)) + min //random numbers between min & max
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```
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### Flush Output Buffer
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```cpp
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#include <stdio.h>
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fflush(FILE); // empty output buffer end write its content on argument passed
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```
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**Do not use stdin** to empty INPUT buffers. It's undefined C behaviour.
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## STRINGS (objects)
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```cpp
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#include <string>
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string string_name = "string_content"; //string declaration
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string string_name = string("string_content"); // string creation w/ constructor
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string.length //returns the length of the string
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//if used after cin >> MUST clear buffer with cin.ignore(), cin.sync() or std::ws
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getline(source, string, delimiter); //string input, source can be input stream (usually cin)
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printf_s("%s", string.c_str()); //print the string as a char array, %s --> char*
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string_1 + string_2; // string concatenation
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string[pos] //returns char at index pos
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```
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### String Functions
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```cpp
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string.c_str() //transforms the string in pointer to char[] (char array aka C string) terminated by '\0'
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```c
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strlen(string); //return length (num of chars) of the string
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strcat(destination, source); //appends chars of string2 to string1
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strncat(string1, string2, nchar); //appends the first n chars of string 2 to string1
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@ -402,7 +301,7 @@ strpbrk(string, charSet); //Returns a pointer to the first occurrence of any
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### String Conversion
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```cpp
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```c
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atof(string); //converts string in double if possible
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atoi(string); //converts string in integer if possible
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atol(string); //converts string in long if possible
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@ -417,52 +316,37 @@ string.c_str(); //reads string char by char
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string.find(substring); // The zero-based index of the first character in string object that matches the requested substring or characters
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```
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## VECTORS
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## Vectors
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```cpp
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```c
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#include <vector>
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vector<type> vector_name = {values}; //variable length array
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```
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## Selection Statements
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## Decision Statements
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### Simple IF
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### If Statements
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```cpp
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if (condition)
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//single instruction
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```c
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if (condition) { }
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if (condition)
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{
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if (condition) {
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//code here
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}
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```
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else if (condition)
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{
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### Simple IF-ELSE
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```cpp
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if (condition) {
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//code here
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} else {
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//code here
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}
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```
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else
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{
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## IF-ELSE multi-branch
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```cpp
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if (condition) {
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//code here
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} else if (condition) {
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//code here
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} else {
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//code here
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}
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```
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### Switch
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```cpp
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```c
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switch (expression) {
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case constant_1:
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//code here
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@ -481,7 +365,7 @@ switch (expression) {
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### While Loop
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```cpp
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```c
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while (condition) {
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//code here
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}
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@ -489,7 +373,7 @@ while (condition) {
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### Do While
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```cpp
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```c
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do {
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//code here
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} while (condition);
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@ -497,20 +381,12 @@ do {
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### For Loop
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```cpp
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```c
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for (initialization; condition; increase) {
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//code here
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}
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```
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### Range-Based For Loop
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```cpp
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for (declaration : range) {
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//code here
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}
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```
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### Break Statement
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`break;` leaves a loop, even if the condition for its end is not fulfilled.
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@ -525,25 +401,14 @@ Functions **must** be declared **before** the main function.
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It is possible to declare functions **after** the main only if the *prototype* is declared **before** the main.
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To return multiple variables those variables can be passed by reference so that their values is adjourned in the main.
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### Function Prototype (before main)
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```c
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type function_name(type argument1, ...); // function prototype
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`type function_name(type argument1, ...);`
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### Standard Function
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```cpp
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type functionName (parameters) { //parametri formali aka arguments
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//code here
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type functionName (parameters) {
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return <expression>;
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}
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```
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### Void Function (aka procedure)
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```cpp
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void functionName (parameters) {
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//code here
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}
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void functionName (parameters) { }
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```
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### Arguments passed by reference without pointers
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@ -551,7 +416,7 @@ void functionName (parameters) {
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Passing arguments by reference causes modifications made inside the function to be propagated to the values outside.
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Passing arguments by values copies the values to the arguments: changes remain inside the function.
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```cpp
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```c
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type functionName (type &argument1, ...) {
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//code here
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return <expression>;
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@ -565,7 +430,7 @@ type functionName (type &argument1, ...) {
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Passing arguments by reference causes modifications made inside the function to be propagated to the values outside.
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Passing arguments by values copies the values to the arguments: changes remain inside the function.
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```cpp
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```c
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type function_name (type *argument_1, ...) {
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instructions;
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return <expression>;
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@ -576,7 +441,7 @@ type function_name (type *argument_1, ...) {
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## Arrays
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```cpp
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```c
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type arrayName[dimension]; //array declaration
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type arrayName[dimension] = {value1, value2, ...}; //array declaration & initialization, values number must match dimension
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@ -584,19 +449,12 @@ array[index] //item access, index starts at 0 (zero)
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array[index] = value; //value assignment at position index
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```
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## String as array of Chars
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```cpp
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char string[] = "text"; //converts string in char array, string length determines dimension of the array
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string str = string[] //a array of chars is automatically converted to a string
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```
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## Array as function parameter
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The dimension is not specified because it is determined by the passed array.
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The array is passed by reference.
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```cpp
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```c
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type function(type array[]){
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//code here
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}
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@ -611,14 +469,14 @@ function(array); //array passed w/out square brackets []
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### Multi-Dimensional Array (Matrix)
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```cpp
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```c
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type matrix[rows][columns];
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matrix[i][j] //element A_ij of the matrix
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```
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### Matrix as function parameter
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```cpp
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```c
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//matrix passed by reference, second dimension is mandatory
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type function(type matrix[][columns]){
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//code here
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@ -634,29 +492,27 @@ type function(type matrix[][dim2]...[dimN]){
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}
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```
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## Record (struct)
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## Structs
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List of non homogeneous items
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### Struct Definition
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### Struct Definition (before functions, outside main)
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```cpp
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struct structName {
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```c
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struct Struct {
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type field1;
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type field2;
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type field3;
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type field4;
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};
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structName variable; //STRUCT variable
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variable.field //field access
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Struct variable; // struct-type variable
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variable.field // field access
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```
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## Pointers
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Pointers hold memory addresses of declared variables, they should be initialized to NULL.
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```cpp
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```c
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type *pointer = &variable; //pointer init and assignment
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type *pointer = NULL;
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type *pointer = otherPointer;
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|
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@ -667,7 +523,7 @@ type **pointerToPointer = &pointer; // pointerToPointer -> pointer -> variabl
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pointer type and variable type **must** match.
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(*) --> "value pointed to by"
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|
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```cpp
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```c
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pointer //address of pointed value (value of variable)
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*pointer //value of pointed variable
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**pointer //value pointed by *pointer (pointer to pointer)
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|
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@ -675,7 +531,7 @@ pointer //address of pointed value (value of variable)
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### Pointer to array
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```cpp
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```c
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type *pointer;
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type array[dim] = {};
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|
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@ -686,7 +542,7 @@ pointer++; //change pointed value to successive "cell" of array
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### Pointers, Arrays & Functions
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|
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```cpp
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```c
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func(array) //pass entire array to function (no need to use (&) to extract address)
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type func(type* array){
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|
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@ -696,7 +552,7 @@ type func(type* array){
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### Pointer to Struct
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```cpp
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```c
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(*structPointer).field //access to field value
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structPointer->structField //access to field value
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```
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|
|
@ -720,7 +576,7 @@ Every node is composed by two parts:
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A **Stack** is a list in with nodes can be extracted from one *side* only (*LIFO*).
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The extraction of an item from the *top* is called **pop**
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|
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```cpp
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```c
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// node structure
|
||||
struct Node {
|
||||
type value;
|
||||
|
|
@ -730,14 +586,14 @@ struct Node {
|
|||
|
||||
#### Node Insertion
|
||||
|
||||
```cpp
|
||||
```c
|
||||
Node *stackNode; //current node
|
||||
Node* head = NULL; //pointer to head of stack
|
||||
|
||||
int nodeValue;
|
||||
//assign value to nodeValue
|
||||
|
||||
stackNode = new Node; //create new node
|
||||
stackNode = (*Node)malloc(sizeof(Node)); //create new node
|
||||
|
||||
stackNode->value = nodevalue; //valorize node
|
||||
stackNode->next = head; //update node pointer to old head adding it to the stack
|
||||
|
|
@ -747,15 +603,15 @@ head = stackNode; //update head to point to new first node
|
|||
|
||||
#### Node Deletion
|
||||
|
||||
```cpp
|
||||
```c
|
||||
stackNode = head->next; //memorize location of second node
|
||||
delete head; //delete first node
|
||||
free(head); //delete first node
|
||||
head = stackNode; //update head to point to new first node
|
||||
```
|
||||
|
||||
#### Passing Head To Functions
|
||||
|
||||
```cpp
|
||||
```c
|
||||
type function(Node** head) //value of head passed by address (head is Node*)
|
||||
{
|
||||
*head = ... //update value of head (pointed variable/object/Node)
|
||||
|
|
@ -783,14 +639,7 @@ 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 manually.
|
||||
|
||||
In **C++**:
|
||||
|
||||
* `new` is used to allocate memory dynamically.
|
||||
* `delete` is use to free the dynamically allocated memory.
|
||||
|
||||
In **C**:
|
||||
C does not automatically free allocated memory when nodes are deleted. It must be done manually.
|
||||
|
||||
* `malloc()` returns a void pointer if the allocation is successful.
|
||||
* `free()` frees the memory
|
||||
|
|
@ -817,7 +666,7 @@ The available classes in C++ to operate on files are:
|
|||
|
||||
Filename can be string literal or CharArray (use `c_str()`).
|
||||
|
||||
```cpp
|
||||
```c
|
||||
ifstream file;
|
||||
file.open("filename"); //read from file
|
||||
|
||||
|
|
@ -838,22 +687,6 @@ 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 combined with the OR operator: `ios::mode | ios::mode`.
|
||||
|
||||
### File Reading & Writing
|
||||
|
||||
To write to and read from a file the `>>` and `<<` operators are used.
|
||||
|
||||
```cpp
|
||||
file.open("filename", ios::in | ios::out);
|
||||
|
||||
file << value << endl; //write to file
|
||||
|
||||
string line;
|
||||
do {
|
||||
getline(file, line); //read file line by line
|
||||
//code here
|
||||
} while (!file.eof()); // or !EOF
|
||||
```
|
||||
|
||||
### Stream state & Input errors
|
||||
|
||||
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.
|
||||
|
|
@ -65,7 +65,7 @@ nav:
|
|||
- GraphQL: graph-ql.md
|
||||
- RegEx: regular-expressions.md
|
||||
- Docker: docker/docker.md
|
||||
- C++: C++/cpp.md
|
||||
- C: c/c.md
|
||||
- Kotlin: kotlin/kotlin.md
|
||||
- Swift: swift/swift.md
|
||||
- Database:
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue