34. Count Set Bits in an 8-bit Register

#include <stdio.h>
#include <stdint.h>

uint8_t count_set_bits(uint8_t reg) {
    uint8_t count = 0;
    while(reg){
        if (reg & 0x1){
            ++count;
        }
        reg >>= 1;
    }
    return count;
}

int main() {
    uint8_t reg;
    scanf("%hhu", &reg);
    printf("%u", count_set_bits(reg));
    return 0;
}