1.运用了除法，取余方式递推出结构
2.运用右移符(>>)运算
3.利用算术与（&）运算

三种方法效率越来越高，减少成本

#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("请输入一个数:\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;}