#include <stdio.h>   // printf
#include <stdlib.h>  // EXIT_SUCCESS

// swap integers a and b in main's stack frame
void swap(int* a, int* b) {
  int tmp = *a;
  *a = *b;
  *b = tmp;
}

int main(int argc, char** argv) {
  int a = 42, b = -7;

  swap(&a, &b);
  printf("a: %d, b: %d\n", a, b);
  return EXIT_SUCCESS;
}