How do I count the number of zero bits in an integer?

Question

How would i go about finding the number of \'zero\' bits in C++. Suppose I have an integer;

int value = 276; 

For which I have the bits 100010

Answer 1

There is a great book for this kind of stuff : Hacker's Delight (yeah, the name sucks : it has nothing to do with security but exclusively bit-twiddling). It provides several algorithms to count '1' bits, the best can also be found here (although the book has explanations that this website doesn't).

Once you know the '1' bits count, just subtract it to the number of bits in your type representation.