求两个数二进制中不同位的个数

题目：

编程实现：两个int（32位）整数m和n的二进制表达中，有多少个位(bit)不同？ 

输入例子:1999 2299

输出例子:7

方法1

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main() {
	int a, b, q, w, s = 0;
	scanf("%d %d", &a, &b);
	for (int i = 32; i > 0; i = i--) {
		q = (a >> i) & 1;
		w = (b >> i) & 1;
		if (q != w)
			s++;
	}
	printf("%d", s);
}

方法2

#include <stdio.h>
int calc_diff_bit(int m, int n){
	int tmp = m^n;
	int count = 0;
	while(tmp){
		tmp = tmp&(tmp-1);
		count++;
	}
	return count;
}

int main(){
 int m,n;
 while(scanf("%d %d", &m, &n) == 2){
     printf("%d\n", calc_diff_bit(m, n));
 }
 return 0;
}