#include<iostream.h>
//定義有兩個虛函數的基類
class Base {
public:
    //定義兩個虛函數
    virtual void aFn1(void){    
        cout<<"aFnl is in Base class."<<endl;
    }
    virtual void aFn2(void) {    
        cout<<"aFn2 is in Base class."<<endl;
    }
    //定義非虛函數
    void aFn3(void) {    
        cout<<"aFn3 is in Base class."<<endl;
    }
};

//派生類Derived_1中重新定義了基類中的虛函數aFn1
class Derived_1:public Base
{
public:
    void aFn1(void) {   //覆蓋aFn1()函數
        cout<<"aFnl is in First derived class."<<endl;
    }
    // void aFn3(void) {   語法錯誤
    //    cout<<"aFn3 is in First derived class."<<endl;
    //}
};

//派生類Derived_2中重新定義了基類中的虛函數aFn2
class Derived_2:public Base{
public:
    void aFn2(void){   //覆蓋aFn2()函數
        cout<<"aFn2 is in Second derived class."<<endl;
    }
    // void aFn3(void) {   語法錯誤
    //    cout<<"aFn3 is in Second derived class."<<endl;
    //}
};
//main()函數的定義
main(void)
{
    //創建和使用基類Base的對象
    Base b;
    cout<<"Base:"<<endl;
    b.aFn1();
    b.aFn2();
    b.aFn3();
    cout<<"----------------------"<<endl;

    //創建和使用派生類Derived_1的對象
    Derived_1 d1;
    cout<<"Derived_1:"<<endl;
    d1.aFn1();
    d1.aFn2();
    d1.aFn3();
    cout<<"----------------------"<<endl;

    //創建和使用派生類Derived_2的對象
    Derived_2 d2;
    cout<<"Derived_2:"<<endl;
    d2.aFn1();
    d2.aFn2();
    d2.aFn3();
}