事件，抢答题

//定义委托

public delegate void QuestionEventHandler(string s);

//定义发布者

public class Publisher

{

public string Question = "太平洋的中间是什么？";

public event QuestionEventHandler QuestionEvent;//事件

public void Ask()

{

Console.WriteLine("提问"+Question);

//判断事件是否被注册

if(QuestionEvent != null)

{

QuestionEvent(Question);

}

}

}

//订阅者1

public class SubscriberA

{

public void OnQuestionAsked(string question)

{//判断条件

if(question == "太平洋的中间是什么？");

Console.WriteLine("甲：平");

else

Console.WriteLine("不知道");

}

}

//订阅者2

public class SubscriberB

{

public void OnQuestionAsked(string question)

{//判断

if(question == "太平洋的中间是什么？");

Console.WriteLine("乙：水");

else

Console.WriteLine("不知道");

}

}

//Main方法调用

class Program

{

static void Main(string[] args)

{

Publisher pub = new Publisher();

SubscriberA a = new SubscriberA();

SubscriberB b = new SubscriberB();

//注册事件

pub.QuestionEvent += a.OnQuestionAsked;

pub.QuestionEvent += b.OnQuestionAsked;

pub.Ask();

}

}