#include <stdio.h>

int f (int i)
{
    return (i + 1);
}

int main (void)
{
  int x = 4;
  int y;
  int (*pf) (int i);
  pf = f;
  y = pf (x);
  printf ("%i + 1 = %i\n", x, y);
  return 0;
}

4 + 1 = 5