剑指Offer面试题：8.二进制中1的个数建议收藏

// 计算整数的二进制表示中1的个数
int CalcOneNumInBinary(int nVal)
{
    int nCount = 0;
    while (nVal > 0)
    {
        if (1 == (nVal & 1))
        {
            nCount ++;
        }

        nVal = nVal >> 1;
    }
    return nCount;
}

int CalcOneNumInBinary_1(int nVal)
{
    int nCount = 0;
    int nFlag = 1;
    while (nFlag > 0)
    {
        if ((nVal & nFlag) > 0)
        {
            nCount ++;
        }

        nFlag = nFlag << 1;
    }
    return nCount;
}

int NumberOf1Solution3(int n)
    {
        int count = 0;

        while (n > 0)
        {
            count++;
            n = (n - 1) & n;
        }

        return count;
    }