931228-1.c

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

f (x)
{
  x &= 010000;
  x &= 007777;
  x ^= 017777;
  x &= 017770;
  return x;
}

main ()
{
  if (f (-1) != 017770)
    abort ();
  exit (0);
}