30. Count Set Bits in an Integer

#include <stdio.h>

#define check_bit(n, pos) ((1 << pos)&n)

int countSetBits(unsigned int n) {
    int count = 0;
    while(n > 0)
    {
        if(check_bit(n, 0))
        {
            count++;
        }
        n>>=1;
    }
    return count;
}

int main() {
    int n;
    scanf("%d", &n);
    printf("%d", countSetBits(n));
    return 0;
}