How To Find The Leading Number Of Zero's In a Number using C

Question

for example,if i have number 64,then its binary representation would be 0000 0000 0000 0000 0000 0000 0100 0000 so leading number of zero\'s is 25. remember i have to calculate

Answer 1

I would go with:

unsigned long clz(unsigned long n) {
    unsigned long result = 0;
    unsigned long mask = 0;
    mask = ~mask;
    auto size = sizeof(n) * 8;
    auto shift = size / 2;
    mask >>= shift;
    while (shift >= 1) {
        if (n <= mask) {
            result += shift;
            n <<= shift;
        }
        shift /= 2;
        mask <<= shift;
    }
    return result;
}