#include <stdio.h>

void swap(int * p, int * q)
{
   int h = *p;
   *p = *q;
   *q = h;
}

int main () {
  int i=4, j=7;
  swap( &i, &j );
  printf("i = %d; j = %d\n", i, j);
  return 0;
}