设计模式一（续）

#include "stdafx.h"
#include<iostream>
#include<string>
#include<vector>
using namespace std;
class Observer;
class Subject;
class Subject
{
public:
    Subject()
    {
        msg="orinal msg";
    }
    void add(Observer &ob)
    {
        vec.push_back(ob);
    }
    void show()
    {
        cout<<"broadcast:msg is:"<<msg<<endl;
    }
    void change(string msg)
    {
        this->msg=msg;
        notification();
    }
    void notification();
private:
    vector<Observer> vec;
    string msg; 

};
class Observer
{
public:
    Observer(Subject &sub):sub(sub)
    {

        this->sub.add(*this); //这里使用了*this  this指的是指向对象本身的指针，*this 指的是对象本身。
    }
    void Showdate()
    {
        sub.show();
    }
private:
    Subject &sub;
};
void Subject::notification()
{
        vector<Observer>::iterator v = vec.begin();
         while( v != vec.end()) {
             (*v).Showdate();
             v++;
      }
 }
int _tmain(int argc, _TCHAR* argv[])
{
    Subject sub= Subject();
    Observer ob1= Observer(sub);
    Observer ob2= Observer(sub);
    sub.change("asdasd");
    return 0;
}