判断二进制有几个1

int several_one(int a)
{
	int count = 0;
	for (int i = 0; i < 32; i++)//只能判断int型
	{
		if (((a >> i) & 1) == 1)
			count++;
	}
	return count;
}

int several_one(int a)
{
	int count = 0;
	while (a != 0)//可以判断任意
	{
		count++;
		a = a & (a - 1);
	}
	return count;
}