面试题40：数组中只出现一次的数字

void FindNumsAppearOnce(int data[], int length, int* num1, int* num2)
{
    if (data == NULL || length < 2)
        return;
 
    int resultExclusiveOR = 0;
    for (int i = 0; i < length; ++ i)
        resultExclusiveOR ^= data[i];
 
    unsigned int indexOf1 = FindFirstBitIs1(resultExclusiveOR);    
 
    *num1 = *num2 = 0;
    for (int j = 0; j < length; ++ j)
    {
        if(IsBit1(data[j], indexOf1))
            *num1 ^= data[j];
        else
            *num2 ^= data[j];
    }
}
 
// 找到num从右边数起第一个是1的位
unsigned int FindFirstBitIs1(int num)
{
    int indexBit = 0;
    while (((num & 1) == 0) && (indexBit < 8 * sizeof(int)))
    {
        num = num >> 1;
        ++ indexBit;
    }
 
    return indexBit;
}

// 判断数字num的第indexBit位是不是1
bool IsBit1(int num, unsigned int indexBit)
{
    num = num >> indexBit;
    return (num & 1);
}