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

Kernighan way of counting set bits

unsigned int v; // count the number of bits set in v
unsigned int c; // c accumulates the total bits set in v
for (c = 0; v; c++)
{
  v &= v - 1; // clear the least significant bit set
}

Can be easily adapted for the task given. A number of iterations here is equal to a number of bits set.

I also recommend the link above for various other ways of solving this and others types of bit-related tasks. There also is a single line example of obtaining bit count implemented in macros.