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  • 观察者模式C++

    一、今日学习内容

    当股票的价格上涨或下降5%时,会通知持有该股票的股民,当股民听到价格上涨的消息时会买股票,当价格下降时会大哭一场。

    c++:

    #include<iostream>
    #include<list>
    using namespace std;
    
    class MyObserver {
    public:
        virtual void response(int rate) {};
    };
    
    class MySubject {
    protected:
        list<MyObserver*>observers;
    public:
        /*注册方法*/
        void attach(MyObserver*observer) {
            observers.push_back(observer);
        };
        /*注销方法*/
        void detach(MyObserver* observer) {
            observers.remove(observer);
        }
    
        /*抽象通知方法*/
        virtual void change(int rate) = 0;
    };
    
    class Stock : public MySubject {
    public:
        void change(int rate) {
            list<MyObserver*>::iterator iter = observers.begin();
            for (; iter != observers.end(); iter++)
                (*iter)->response(rate);
        }
    };
    
    class Holders :public MyObserver {
    public:
        void response(int rate) {
            if (rate >= 5) {
                cout << "股票上涨,购买股票" << endl;
            }
            else if (rate <= -5) {
                cout << "股票下跌,大哭一场" << endl;
            }
            else {
                cout << "股票还比较稳定哦~" << endl;
            }
        }
    };
    
    int main() {
        MySubject* subject = new Stock();
        MyObserver*obs1 = new Holders();
        subject->attach(obs1);
        cout << "----------------------股票上涨-----------------------" << endl;
        subject->change(5);
        cout << endl;
        cout << "----------------------股票下跌-----------------------" << endl;
        subject->change(-5);
        cout << endl;
        cout << "----------------------股票稳定-----------------------" << endl;
        subject->change(4);
        cout << endl;
    }

    截图:

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  • 原文地址:https://www.cnblogs.com/wmdww/p/15578971.html
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