寫(xiě)一個(gè)函數(shù)返回參數(shù)二進(jìn)制中 1 的個(gè)數(shù)（三種方法）

1.運(yùn)用了除法，取余方式遞推出結(jié)構(gòu)
2.運(yùn)用右移符(>>)運(yùn)算
3.利用算術(shù)與（&）運(yùn)算

三種方法效率越來(lái)越高，減少成本

#include<stdio.h>

int Number1(int n)
{
    int k;
    int count=0;
    while (n > 0)
    {
        k = n % 2;
        n /= 2;
        if (1 == k)
        {
            count++;
        }
    }
    return count;
}

int Number2(int n)
{
    int count = 0;
    while (n>0)
    {
        if ((n & 1) == 1)
        {
            count++;
        }
        n = n >>1 ;
    }
    return count;
}

int Number3(int n)
{
    int count = 0;
    while (n)
    {
        n = n&(n - 1);
        count++;
    }
    return count;
}
int main()
{
    int n;
    printf("請(qǐng)輸入一個(gè)數(shù):\n");
    scanf("%d",&n);
    int ret1=Number1(n);
    printf("%d\n",ret1);
    int ret2 = Number2(n);
    printf("%d\n",ret2);
    int ret3 = Number3(n);
    printf("%d\n",ret3);
    system("pause");
    return 0;
}