访问派生类C ++的私有成员

问题描述

我试图通过基类的对象访问派生类的私有成员.这是我想做的事情:

I am trying to access derived class' private members via an object of the base class. Here is what I'm trying to do :

 class A {

      private:

           int a, b;

      public:
           A(_a, _b) : a(_a), b(_b) {}
           int getA() { return a; }
           int getB() { return b; }
 };

 class B : public A {

      private:
           int c;

      public:
           B(_a, _b, _c) : A(_a, _b), c(_c) {}
           int getC() { return c; }

 };

 vector<A*> objects;
 A* retVal = new B(1,2,3);
 objects.push_back(retVal);

现在怎么可能访问它?

 objects[0] -> getC();

我有点困惑.

谢谢.

推荐答案

如果您知道对象实际上是派生类型B，则可以执行以下操作:

If you know the object is actually of derived type B, you can do this:

static_cast<B*>(objects[0])->getC();

如果您错了，并且该对象实际上不是B类型(或B的子类)，则您的程序将调用未定义的行为，所以不要这样做.

If you are wrong and the object is not actually of type B (or a subclass of B), your program will invoke undefined behavior, so don't do that.

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