Solutions I recieved so far on the C riddle

This is a list on the solutions I got from various people on the C riddle, that m3ntor brought up on #demo-gr a couple of days ago.

The riddle goes like this: increment an unsigned int by one in C, without using any of the operators +, -, ++, --, +=, -=, and without any library function calls.

personsolution
m3ntor and samurai 
unsigned int num;
num = ~num * 0xffffffff;
Nuclear 
unsigned int num;
num = &((char*)num)[1];
imak 
unsigned int num;
unsigned int w=1, t=num;
while((t^=w)<num)w<<= 1;
num=t;
xtapodi_kataifi 
unsigned int num;
unsigned int y = 1;
while(num & y) {
    num = num ^ y;
    y = y << 1;
}
num = num | y;
Bartosz Dobrzeleck 
unsigned int inc(unsigned int num)
{
    unsigned int k = 1, l;
    while(k <= num) {
        if((k & num) == 0) {
            l=k;
            while(l > 1) {
                num >>= 1;
                l >>= 1;
            }
            l=k;
            while(l > 1) {
                num <<= 1;
                l >>= 1;
            }
            num |= k;
            return num;
        }
        k <<= 1;
    }
    return k;
}