#include <stdio.h>

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 0;
}