C ++中的公共和私有继承 [英] Public and private inheritance in C++

问题描述

从文献中我们知道对于公共继承，子类（子类）的对象也可以被认为是基类（超类）的对象。为什么当继承受保护或私有时，子类的对象不能被认为是超类的对象？

As we know from the literature for the public inheritance the object of child class (sub-class) also can be considered as the object of base class (super-class). Why the object of the sub-class can’t be considered as an object of super-class, when the inheritance is protected or private?

推荐答案

因为你看不到它：

class Base
{
    public: virtual ~Base() {}
};

class PublicDerived: public Base
{    };

class PrivateDerived: private Base
{    };

int main()
{
    PublicDerived   publicD;
    PrivateDerived  privateD;

    Base&           base1 = publicD;
    Base&           base2 = privateD; // ERROR
} 

$ b $ p

所以你不能使用PrivateDerived对象，

所以它永远不会像一个Base类对象。

So you can not use a PrivateDerived object where a Base object could be used.
So it will never act like a Base class object.

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