c++在派生类中使用基类函数的错误

Question

#include <iostream>

class ZZ
{
public:
    void print()
    {
        std::cout << "hello\n";
    }
};

class YY : public ZZ
{
public:
    void print()
    {
        using ZZ::print;
        print();
    }
};

int main()
{
    YY temp;
    temp.print();
    getchar();
    return 0;
}

为什么上面的这段代码回报错？
error: 'ZZ' is not a namespace or unscoped enum using ZZ::print;

Answer 1

Because your usage is wrong, this usage is c++11newly added

class YY : public ZZ
{
public:
    using ZZ::print;
};

If you write it in a member function, it will extend the scope of a member function, which of course will not succeed. .

Answer 2

First of all, the temp in main does not initialize the instance. . Then your subclass YY overloads the method of the parent class. Don’t write USING, just ZZ::print();

Answer 3

To use the public function of the base class in a derived class, either you do not override it directly, or you can use ZZ::print() call in the print function in the derived class.

Answer 4

Using is written in the wrong place! It should not be written inside a member function! In addition, if the two print functions have the same name, infinite recursion will occur. The print in YY should be renamed!

class YY : public ZZ
{
public:

using ZZ::print;
void YYprint()
{
    print();
}

};