函数返回值1的数量

方法一：

#include<stdio.h>
int count_one_bits(unsigned int value)
{
	int count = 0;
	while(value)
	{
		if( value%2 == 1)
			count ++;
		value = value/2;
	}
	return count;
}
int main()
{
	int ret = 0;
	ret = count_one_bits(15);
	printf("%d\n",ret);
	//printf("%d\n",count_one_bits(ret));
	return 0;
}

方法二：

#include<stdio.h>
int count_one_bits_1(unsigned int value)
{
	int count = 0;
	while(value)
	{
		count ++;
		value = value &(value - 1);
	}
	return count;
}
int main()
{
	int ret = 0;
	ret = count_one_bits_1(15);
	printf("%d\n",ret);
	//printf("%d\n",count_one_bits(ret));
	return 0;
}

方法三：

#include<stdio.h>

int count_one_bits_2(unsigned int value)
{
	int count = 0;
	while(value)
	{
		if(value%2 == 1)
		{
			count ++;
			value =value>>1;
		}
	}
	return count;
}
int main()
{
	int ret = 0;
	ret = count_one_bits_2(15);
	printf("%d\n",ret);
	//printf("%d\n",count_one_bits(ret));
	return 0;
}