C++派生继承中的一个问题！

 

#include "iostream.h"

class A...{
public:
        int num;
        A()...{
                num = 1;
        }
        virtual void Display()...{
                cout <<"A";
        }
        void print()...{
                cout << num;
        }
        static void show()...{
                A a;
                a.Display();
                a.print();
        }
};

class B:public A...{
public:

        int num;
    B()...{
                num = 2;
        }
        void Display()...{
                cout <<"B";
        }
        void print()...{
                cout << num;
        }
        virtual void show()...{
                Display();
                print();
        }
};

class C:public B...{
public:
        int num;
    C()...{
                num = 3;
        }
        void Display()...{
                cout <<"C";
        }
        virtual void print()...{
                cout << num;
        }
        void show()...{
                Display();
                A::print();
        }
};

void main()
...{
                B *b = new C;
                cout<<"b->num="<<b->num<<endl;
}

继承之后
类B中的num不会覆盖A中的num，继承之后B中A中的num不可见，除非A：：num才可以
类C中的num也不会覆盖B和A中的num，也是同样的道理
当一个c对象地址转成B地址，可见的就是B类中num，所以打印出来的就是2