mirror of
https://github.com/LeCoupa/awesome-cheatsheets.git
synced 2026-01-28 22:28:02 -08:00
48 lines
2.4 KiB
Markdown
48 lines
2.4 KiB
Markdown
<!-- making C cheatsheets -->
|
|
|
|
```main() Function```
|
|
|
|
* The main() function is the starting point of the program: ```int main (int argc, char *argv[])```
|
|
* The return type of the main() function is an integer (type int) and it is known as the ```return value``` of the program.
|
|
* As a rule of thumb, ```value 0 means success while non-zero means an error conditions.```
|
|
|
|
---
|
|
|
|
## Include Files
|
|
|
|
* The `purpose` of these files is to tell the compiler about the existence of external functions which the source code will make use of.
|
|
|
|
---
|
|
|
|
## Preprocessor directives:
|
|
|
|
| Directive | Description |
|
|
|-----------------------------|----------------------------------------------------|
|
|
| `#include "mine.h"` | Search current working directory first. |
|
|
| `#include <stdio.h>` | Search command line directory, then the system. |
|
|
| `#define TRUE 1` | Macro substitution, usually use capitals. |
|
|
| `#define min(a,b)` | Macro substitution with parameters. |
|
|
| `#define abs(a)` | Macro substitution. |
|
|
| `#define note /* comment */` | This comment gets inserted every time `note` appears. |
|
|
| `backslash \ at end of a line` | Means continue the line. |
|
|
| `#undef TRUE` | Undefines a previously defined macro name. |
|
|
| `#error` | Stop compiling at this point. |
|
|
| `#if expression` | Conditional compilation, starts an `if` structure. |
|
|
| `#elif expression` | Else if expression != 0, compile the following code. |
|
|
| `#else` | Else, compile the following code. |
|
|
| `#endif` | End of conditional compiling. |
|
|
| `#ifdef macroname` | Like `#if`, compiles if `macroname` is defined. |
|
|
| `#ifndef macroname` | Like `#if`, compiles if `macroname` is undefined. |
|
|
| `#line number [filename]` | Set the origin for `__LINE__` and `__FILE__`. |
|
|
| `#pragma` | Gives the compiler commands. |
|
|
|
|
---
|
|
|
|
## Create and execute a program
|
|
|
|
In Linux systems:
|
|
1. Open up a terminal (Ctrl + Alt + T)
|
|
2. Create the program: nano nameProgram.c
|
|
3. Write the program and save it
|
|
4. gcc -o nameExecutable nameProgram.c (eg: gcc -o nameProgram_output nameProgram.c
|
|
) |