921202-2.c

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

int
f(long long x)
{
  x >>= 8;
  return x & 0xff;
}

main()
{
  if (f(0x0123456789ABCDEFLL) != 0xCD)
    abort();
  exit (0);
}