CareerCup

int integralPartOfLog(unsigned int n)
{

    int ret = 0;
    
    while (n > 0) {
        n = n>>1;
        ret++;
    }
    
    return ret-1;
}

I think that's the most obvious way of solving the question.
graphics.stanford.edu/~seander/bithacks.html#IntegerLogObvious

@Game programmer -- what's wrong with that code?

That's the most obvious solution to the problem. This also states that
graphics.stanford.edu/~seander/bithacks.html#IntegerLogObvious
@Game programmer -- what's wrong with it?

int log2(int a)
{
int n=0;
while(a>1)
{
a>>=1;
n++;
}
return n;
}

One of the worst things a candidate can do, which you have done, is not pay attention to the question. When I'm on a phone interview with a candidate who does this, I say thank you very much for your time, best of luck in your job search and terminate the interview. You may think that is harsh but if you can't listen and understand a question, there is little chance you're going to be successful in an environment where communication skills are a critical and key skill.