1  int
       2  f (int n)
       3  {
       4    return (n > 0) - (n < 0);
       5  }
       6  
       7  main ()
       8  {
       9    if (f (-1) != -1)
      10      abort ();
      11    if (f (1) != 1)
      12      abort ();
      13    if (f (0) != 0)
      14      abort ();
      15    exit (0);
      16  }