[C] 計算數值有幾個 1

利用shift 方式

可以搭配這個網站，線上執行
https://ideone.com/i1sUId#cmperr

#include <stdio.h>
#include <stdlib.h>
int ret_one_bit_num(unsigned int);
void main(){
    int rlt = 0, input = 9;

    rlt = ret_one_bit_num(input);
    printf("%d have [%d] bit  is 1\r\n", input, rlt);
    system("pause");
}
int ret_one_bit_num(unsigned int n)
{
    int count = 0;
    while(n!=0)
    {
        if(n & 1 == 1)
            count++;
        n>>=1;
    }    
    return count;
}