5.16

#include <iostream>

using namespace std;

class BaseClass

{

public:

    void fn1();

    void fn2();

};

void BaseClass::fn1()

{

    cout << "调用基类的函数fn1()" << endl;

}

void BaseClass::fn2()

{

    cout << "调用基类的函数fn2()" << endl;

}

class DerivedClass :public BaseClass  {

public:

    void fn1();

    void fn2();

};

void DerivedClass::fn1()

{

    cout << "调用派生类的函数fn1()" << endl;

}

void DerivedClass::fn2()

{

    cout << "调用派生类的函数fn2()" << endl;

}

int main()

{

    DerivedClass aDerivedClass;

    DerivedClass* pDerivedClass = &aDerivedClass;

    BaseClass* pBaseClass = &aDerivedClass;

    aDerivedClass.fn1();

    aDerivedClass.fn2();

    pBaseClass->fn1();

    pBaseClass->fn2();

    pDerivedClass->fn1();

    pDerivedClass->fn2();

    return 0;

}