派生类继承基类的赋值运算符？ [英] Derived class inherit base class assignment operator?

问题描述

在我看来，Derived类不继承基类赋值运算符

如果Derived类继承Base类赋值运算符，请解释下面的示例

It seems to me that Derived class don't inherit base class Assignment operator
if Derived class inherit Base class assignment operator , can you please explain the following example

在下面的代码中我覆盖了基类operator =在Derived中，所以Derived类默认赋值操作符调用重载operator =

In the following code I am overriding base class operator= in Derived, so that Derived class default assignment operator calls overloaded operator=

#include <iostream>  
using namespace std;      
class Base  
{  
    public:  
    Base(int lx = 0):x(lx)  
    {  
    }  

    virtual Base& operator=( const Base &rhs)  
    {  
        cout << "calling Assignment operator in Base" << endl;  
        return *this;  
    }

    private:  
    int x;     
};      


class Derived : public Base  
{  
    public:  
    Derived(int lx, int ly): Base(lx),y(ly)  
    {  
    }

    Base& operator=(const Base &rhs)  
    {  
        cout << "Assignment operator in Derived"<< endl;  
        return *this;  
    }  

    private:  
    int y;    
};  



int main()  
{  
    Derived d1(10,20);  
    Derived d2(30,40);  
    d1 = d2;  
}  

它提供输出

在Base中调用赋值运算符

calling Assignment operator in Base

我已将基类operator =重写为派生类，所以如果派生类继承基类operator =，那么它应该被operator =（我已经写在派生类中）覆盖，现在Derived类default operator =应该调用覆盖版本，而不是从基类operator =。

I have re-written base class operator= into derived class, so if derived class inherits base class operator= then it should be get overridden by operator= (that i have written in derived class), and now Derived class default operator= should call overridden version and not from the base class operator=.

推荐答案

编译器为Derived生成一个默认赋值运算符但是，默认赋值运算符会调用类的成员和基类的所有赋值运算符。

The compiler generates a default assignment operator for Derived (which hides the operator of Base). However, the default assignment operator calls all assignment operators of the class' members and base classes.

这篇关于派生类继承基类的赋值运算符？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！