Simplest C program

Preferred

#include <stdio.h>

int main(void)
{

  return (0);
}


Accepted but not standard

#include <stdio.h>

void main(void)
{

}

Simple program with a function call and a procedure (void function) call that actually do something. The whole program is in one file.

/** Program header goes here **/

#include <stdio.h>

int value_returning_function(int);
void procedure(int, int);

int main(void)
{
  int answer;

  answer = value_returning_function(2);
  procedure(2, answer);
  return (0);
}


/** function header should be here **/
int value_returning_function(int val)
{
  return (val * 2);
}


/** function header should be here **/
void procedure(int val1, int val2)
{
  printf("\nValue 1 = %d and Value 2 = %d\n", val1, val2);
  return; /* The return is optional - used for completeness */
}