父类子类指针相互转换问题

#include <iostream>
using namespace std;
class Base {
public:
    virtual void f() { cout << "Base::f" << endl; }
    virtual void g() { cout << "Base::g" << endl; }
            void h() { cout << "Base::h" << endl; }

};
class Derived:public Base
{
public:
    virtual void f(){cout<<"Derived::f"<<endl;}
            void g(){cout<<"Derived::g"<<endl;}
            void h(){cout<<"Derived::h"<<endl;}
};


void main()
{
    Base *pB=new Base();
    cout<<"当基类指针指向基类对象时："<<endl;
    pB->f();
    pB->g();
    pB->h();
    cout<<endl;

    Derived *pD=(Derived*)pB;
    cout<<"当父类指针被强制转换成子类指针时："<<endl;
    pD->f();
    pD->g();
    pD->h();
    cout<<endl;

    Derived *pd=new Derived();
    cout<<"当子类指针指向子类时候"<<endl;
    pd->f();
    pd->g();
    pd->h();
    cout<<endl;

    Base *pb=(Base *)pd;
    cout<<"当子类指针被强制转换成父类指针时："<<endl;
    pb->f();
    pb->g();
    pb->h();
    cout<<endl;

    Base *pp=new Derived();
    cout<<"父类指针指向子类对象时候："<<endl;
    pp->f();
    pp->g();
    pp->h();
    cout<<endl;
}