programming-examples/c/Bitwise/C Program to Count Number of bits set to 0 in an Integer.c

/*
 * C Program to Count Number of bits set to 0 in a Integer x
 */
#include <stdio.h>
#define NUM_BITS_INT (8*sizeof(int))

int count_unset(int);

int main()
{
    int i, num, snum, res, count = 0;
    printf("\nEnter the number");
    scanf("%d", &num);
    /*
     * Check each bit whether the bit is set or unset
     * Uses >> and & operator for checking individual bits
     */
    for (i = 0; i <= NUM_BITS_INT; i++)
        {
            snum = num >> i;
            res = snum & 1;
            if (res == 0)
                count++;
        }
    printf("%d", count);
}