# File
## .exe
The file that can be executed , this is the so-called program .
## .c
.c file contains the **main** function and can be compiled to become an .exe file .
## .h
.h file is the tool box of .c , it can contain functions , structures , global variables .....etc . The only diffrence between .c and .h is that .h don't contains **main** . .h file is often be used as a big function box , with many useful functions .
```graphviz
Digraph G{
node[shape = box ]
".c" -> ".exe"
".h" -> ".c"
}
```
## Common Format for .c
```clike=
#include <stdio.h>
int main(){
operation ;
return 0 ;
}
```
The .h above can be any , depends on the funtion you wish to call .