观察者模式（二）

#include<iostream>
#include<list>
#include<string>
using namespace std;
class Observer{
protected:
    string name;
public:
    virtual void buy()=0;
    virtual void cry()=0;
};
class Gumin:public Observer{
public:
    Gumin(string name){
        this->name=name;
    }
    void buy(){
        cout<<"股民"<<name<<"买了该股票"<<endl;
    }
    void cry(){
        cout<<"股民"<<name<<"哭了"<<endl;
    }
};
class Subject{
protected:
    list<Observer*> observers;
public:
    void attach(Observer *obs){
        observers.push_back(obs);
    }
    void detach(Observer *obs){
        observers.remove(obs);
    }
    virtual void up()=0;
    virtual void down()=0;
};
class Gufen:public Subject{
public:
    void up(){
        cout<<"---股份上涨5%---"<<endl;
        list<Observer*>::iterator iter = observers.begin();
        for(; iter != observers.end(); iter++)
            (*iter)->buy();
    }
    void down(){
        cout<<"---股份下跌5%---"<<endl;
        list<Observer*>::iterator iter = observers.begin();
        for(; iter != observers.end(); iter++)
            (*iter)->cry();
    }
};
int main(){
    Observer *obs1,*obs2;
    obs1=new Gumin("张三");
    obs2=new Gumin("王五");
    Subject *sub;
    sub=new Gufen();
    sub->attach(obs1);
    sub->attach(obs2);
    sub->up();
    sub->down();
}