#include <stdio.h>

// we define a macro to swap to variables:
#define   SWAP(A,B)   temp__yzVBZq = A; A = B; B = temp__yzVBZq

// global variable used by the above macro:
int temp__yzVBZq;
// Why do we use this crazy name?

int main(void) {

  // our two variables:
  int one = 1, two = 2;

  // now, we do not want to swap them:
  if (0) SWAP(one,two);

  // look at the result:
  printf("one = %d, two = %d\n", one, two);
  
  // end:
  return 0;
}