this is a gcc file, you can download it and learn its usetility, for further detail please look at t

				int a[2];								f (b)				{				  unsigned int i;				  int *p;				  for (p = &a[b], i = b; --i < ~0; )				    *--p = i * 3 + (int)a;				}								main ()				{				  a[0] = a[1] = 0;				  f (2);				  if (a[0] != (int)a || a[1] != (int)a + 3)				    abort ();				  exit (0);				}