I don't understand what you mean. Decrementing from 0 gives you 0xFFFF, incrementing from 0xFFFF gives you zero. (It doesn't matter whether you use unsigned or

I don't understand what you mean. Decrementing from 0 gives you 0xFFFF, incrementing from 0xFFFF gives you zero. (It doesn't matter whether you use unsigned or signed increment as those are the same operation, at least on a two's-complement processor, where the bit pattern 0xFFFF represents -1.) You could do this trick on a machine that uses signed-magnitude representation, since a signed increment of 0xFFFF (INT_MIN) would result in 0xFFFE (INT_MIN + 1). But all modern processors use two's complement.