#include<iostream.h>
//定義抽象類
class Base {
public:
    //定義兩個純虛函數
    virtual void aFn1(void)=0;
    virtual void aFn2(void)=0;
};

//派生類Derived_1中覆蓋了基類中的純虛函數
class Derived_1:public Base
{
public:
    void aFn1(void) {
        cout<<"aFnl is in First derived class."<<endl;
    }
    void aFn2(void) {
        cout<<"aFn2 is in First derived class."<<endl;
    }
};

//派生類Derived_2中覆蓋了基類中的純虛函數
class Derived_2:public Base{
public:
    virtual void aFn1(void){
        cout<<"aFn1 is in Second derived class."<<endl;
    }
    void aFn2(void){
        cout<<"aFn2 is in Second derived class."<<endl;
    }
};

//main()函數中測試抽象類及其派生類的對象
main(void)
{
    //用抽象類不能創建對象
    //    Base b;  語法錯誤
    //    b.aFn1();
    //    b.aFn2();

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

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