Observer

observer.h
#ifndef OBSERVE_H
#define OBSERVE_H
#include "iostream"
using namespace std;

class Observer
{
public:
    Observer();
    virtual void update(int hour, int min, int sec) = 0;
};

#endif // OBSERVE_H

observer.cpp
#include "observer.h"

Observer::Observer()
{

}

subject.h
#ifndef SUBJECT_H
#define SUBJECT_H
#include <list>
#include "observer.h"
using namespace std;

class Subject
{
public:
    Subject();
    void registerObserver(Observer *ob);
    void removeObserver(Observer *ob);

    virtual void notify() = 0;
protected:
    list<Observer *> lo;
};

#endif // SUBJECT_H

subject.cpp
#include "subject.h"

Subject::Subject()
{

}

void Subject::registerObserver(Observer *ob)
{
    lo.push_back(ob);
}

void Subject::removeObserver(Observer *ob)
{
    lo.remove(ob);
}

bejingtime.h
#ifndef BEIJINGTIME_H
#define BEIJINGTIME_H
#include "subject.h"

class BeijingTime : public Subject
{
public:
    BeijingTime();
    void setTime(int hour, int min, int sec);
    void notify();
    void dis()
    {
        cout << "hour:" << _hour << "min:" << _min << "sec:" << _sec << endl;
    }

protected:
    int _hour;
    int _min;
    int _sec;
};

#endif // BEIJINGTIME_H

beijingtime.cpp
#include "beijingtime.h"

BeijingTime::BeijingTime()
{

}

void BeijingTime::notify()
{
    list<Observer *>::iterator itr;
    for(itr = lo.begin(); itr != lo.end(); ++itr)
    {
        (*itr)->update(_hour, _min, _sec);
    }
}

void BeijingTime::setTime(int hour, int min, int sec)
{
    _hour = hour;
    _min = min;
    _sec = sec;
    notify();
}

canadatime.h
#ifndef CANADATIME_H
#define CANADATIME_H
#include "observer.h"

class CanadaTime : public Observer
{
public:
    CanadaTime();
    void update(int hour, int min, int sec);
    void dis()
    {
        cout << "hour:" << _hour << "min:" << _min << "sec:" << _sec << endl;
    }
private:
    int _hour;
    int _min;
    int _sec;
};

#endif // CANADATIME_H

canadatime.cpp
#include "canadatime.h"

CanadaTime::CanadaTime()
{

}

void CanadaTime::update(int hour, int min, int sec)
{
    _hour = hour + 100;
    _min = min;
    _sec = sec;
}

londontime.h
#ifndef LONDONTIME_H
#define LONDONTIME_H
#include "observer.h"

class LondonTime : public Observer
{
public:
    LondonTime();
    void update(int hour, int min, int sec);
    void dis()
    {
        cout << "hour:" << _hour << "min:" << _min << "sec:" << _sec << endl;
    }
private:
    int _hour;
    int _min;
    int _sec;
};

#endif // LONDONTIME_H

londontime.cpp
#include "londontime.h"

LondonTime::LondonTime()
{

}

void LondonTime::update(int hour, int min, int sec)
{
    _hour = hour + 200;
    _min = min;
    _sec = sec;
}

tokyotime.h
#ifndef TOKYOTIME_H
#define TOKYOTIME_H
#include "observer.h"

class TokyoTime : public Observer
{
public:
    TokyoTime();
    void update(int hour, int min, int sec);
    void dis()
    {
        cout << "hour:" << _hour << "min:" << _min << "sec:" << _sec << endl;
    }
private:
    int _hour;
    int _min;
    int _sec;
};

#endif // TOKYOTIME_H

tokyotime.cpp
#include "tokyotime.h"

TokyoTime::TokyoTime()
{

}

void TokyoTime::update(int hour, int min, int sec)
{
    _hour = hour + 300;
    _min = min;
    _sec = sec;
}

main.cpp
#include <iostream>
#include "tokyotime.h"
#include "londontime.h"
#include "canadatime.h"
#include "beijingtime.h"
using namespace std;

int main(int argc, char *argv[])
{
    TokyoTime tt;
    LondonTime lt;
    CanadaTime ct;
    BeijingTime bt;
    bt.registerObserver(&tt);
    bt.registerObserver(&lt);
    bt.registerObserver(&ct);
    bt.setTime(100, 200, 300);
    bt.dis();
    tt.dis();
    lt.dis();
    ct.dis();
    return 0;
}