On 05/16/2012 03:02 PM, Charles Chance wrote: Hello, Don't know if this is related, but the statement above hides a nasty bug: p[1] is a char (as for the description), so is signed, shifting to the left 16 bits is ok, as an integral promotion takes place. The problem is that if p[1] is negative (-1 is 0xff), then the integral promotion is signed as well and is complementary of 2 (or whatever the implementation considers), and the shift will return another value as expected. For example : #include <stdio.h> int main(){ char b = 0xff; unsigned h = (b<<16); printf("%x\n", h); return 0; } will print ffff0000 instead of ff0000 as expected. Haven't calculated the implication of this related to the bug. An fix would be to cast p[1] to (unsigned char) Cheers, Marius -- Zbihlei Marius Head of Linux Development Services Romania 1&1 Internet Development srl Tel KA: 754-9152 Str Mircea Eliade 18 Tel RO: +40-31-223-9152 Sect 1, Bucuresti mailto: marius.zbihlei(a)1and1.ro 71295, Romania