今天看到一个委托类型的练习，有点不是很清楚，
其中代码如下：
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using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class shijian : System.Web.UI.Page
{
public class Book
{
string title; // 标题
int num; // 书的数量
double price; //价钱
public delegate void TitleChangeHandler();//事先声明一个委托类型
public event TitleChangeHandler TitleChange;//声明一个事件，并指定是委托类型
public Book()
{
}
public Book(string ntitle, int nnum, double nprice)
{
title = ntitle;
num = nnum;
price = nprice;
}
public string Title
{
get
{
return title;
}
set
{
title = value;
TitleChange(); //修改标题会触发这个事件
}
}
public int Num
{
get
{
return num;
}
set
{
num = value;
}
}
public double Price
{
get
{
return price;
}
set
{
price = value;
}
}
public string BookInfo()
{
string html = "<BR>书名是： " + title + "<BR>数量：" + num + "本<BR>价钱：" + price;
return html;
}
}
protected void Page_Load(object sender, EventArgs e)
{
Book shu = new Book();
shu.TitleChange += new Book.TitleChangeHandler(shu_TitleChange);
shu.Title = "book name";
shu.Num = 21;
shu.Price = 10.123;
Response.Write(shu.BookInfo());
}
void shu_TitleChange()
{
Response.Write(" 事件执行完成");
}
}
代码结束
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运行结果：
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今天是:2008-06-06
