Function

/* proto.c -- uses a function prototype */
#include <stdio.h>
int imax(int, int);        /* prototype */
int main(void)
{
    printf("The maximum of %d and %d is %d.\n",
           3, 5, imax(3, 5)); 
    printf("The maximum of %d and %d is %d.\n",
           3, 5, imax(3.0, 5.0));
    return 0;
}

int imax(int n, int m)
{
    return (n > m ? n : m);
}