This directive includes another file into the current one at the exact location of the directive..

 #include "file.h"                //  includes a header file into the project

 #include <stdint.h>           //  includes compiler internal header file

Example:

 
#include <stdint.h>

#include "foo.h"

void main()

{

    // if <stdint.h> is included, you can use the short type names like int32_t

    int32_t expr = 10;

    while (expr)

    {

      printf("%d",expr);

      expr--;

      if(expr == 5)

       break;

    }

    foo();

}