#include <stdio.h>
#include <iostream>

using namespace std;

class Stock1{
public:
    void Sell(){ cout<<"stock1 sell\n";};
    void Buy(){ cout<<"stock1 out\n";};
};


class Stock2{
public:
    void Sell(){ cout<<"stock2 sell\n";};
    void Buy(){ cout<<"stock2 out\n";};
};

class Stock3{
public:
    void Sell(){ cout<<"stock3 sell\n";};
    void Buy(){ cout<<"stock3 out\n";};
};


class Fund{
    Stock1 * gu1;
    Stock2 * gu2;
    Stock3 * gu3;
    
    
public:
    Fund(){
        gu1 = new Stock1();
        gu2 = new Stock2();
        gu3 = new Stock3();
    }
    void sell(){
        gu1->Sell();
        gu2->Sell();
        gu3->Sell();
    };
    void buy(){
        gu1->Buy();
        gu2->Buy();
        gu3->Buy();
    }
};

void testLesson8(){
    Fund * fund = new Fund();
    fund->buy();
    fund->sell();
}

簡單的不能再簡單了，為了使技術(shù)分層時(shí)將每層的技術(shù)做一定的封裝，可以讓高層用戶不需要改動(dòng)