有陷阱，要考虑溢出问题

 

int comp_int(int var1, int var2)/* return value < 0: means var1 < var2;  *              = 0: means var1 = var2; *              > 0: means var1 > var2;*/{    int bit_width, msb, rtnvar;    bit_width = sizeof(int) << 3;        msb = var2 >> (bit_width -1) -           var1 >> (bit_width -1);    if (msb)        rtnvar = msb;    else        rtnvar = var1 - var2;    return rtnvar;}