product.c

/*
  Description:
  The "beauty" of C macro.
*/

#include <stdio.h>

#define PRODUCT(x) (x * x)

int main(int argc, char**argv)
{
  int i = 3, j, k;

  /*
    j is 9.
  */
  j = PRODUCT(i++);

  /*
    k is 49.
  */
  k = PRODUCT(++i);

  printf("%d %d\n", j, k);

  return 0;
}

/*
$ cpp product.c | tail -18
int main(int argc, char**argv)
{
  int i = 3, j, k;




  j = (i++ * i++);




  k = (++i * ++i);

  printf("%d %d\n", j, k);

  return 0;
}
*/