详细介绍有关于.NET的委托
发布时间：2020-12-15 21:12:33 所属栏目：asp.Net 来源：网络整理
导读：span style="FONT-SIZE: 10pt"? .NET学习中，你碰到过委托吗？我接触.NET几个月以来，关于委托的确花了我好长时间才弄明白，这里我就C#中的委托给大家介绍一下。（先说定义和特征，然后用例子说明） p style="FONT-SIZE: 10pt"??? 委托是回调函数的类型安全
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<span style="FONT-SIZE: 10pt">? .NET学习中，你碰到过委托吗？我接触.NET几个月以来，关于委托的确花了我好长时间才弄明白，这里我就C#中的委托给大家介绍一下。（先说定义和特征，然后用例子说明） <p style="FONT-SIZE: 10pt">??? C#中的委托类似于C或C++中的函数指针。使用委托使程序员可以将方法引用封装在委托对象内（ 所以这里的“引用”不是原始内存地址，而是包装了方法的内存地址的委托实例 ）。然后可以将给委托对象传递可调用所引用方法的代码，而不必在编译时知道将调用哪个方法。与C或C++中的函数指针不同，委托是面向对象、类型安全的，并且是安全的。 <p style="FONT-SIZE: 10pt">??? 委托声明定义一种类型，它用一组特定的参数以及返回类型封装方法。 <p style="FONT-SIZE: 10pt">??? 对于静态方法，委托对象封装要调用的方法。 <p style="FONT-SIZE: 10pt">??? 对于实例方法，委托对象同时封装一个实例和该实例上的一个方法。 <p style="FONT-SIZE: 10pt">??? 如果你有一个委托对象和一组适当的参数，则可以用这些参数调用该委托。 <p style="FONT-SIZE: 10pt">??? 委托的一个有趣且有用的属性是： 它不知道或不关心自己引用的对象的类。任何对象都可以，知识方法的参数类型必须与委托的参数类型和返回类型相匹配。这是的委托完全适合“匿名”调用。 <p style="FONT-SIZE: 10pt">??? 到现在已经说得不少了，现在开始用例子说明如何声明、实例化和调用委托：下面的示例中，BookDB 类封装一个书店数据库，它维护一个书籍数据库。它公开 ProcessPaperbackBooks 方法，该方法在数据库中查找所有平装书，并为每本书调用一个委托。所使用的 delegate 类型称为 ProcessBookDelegate.Test 类使用该类输出平装书的书名和平均价格。委托的使用促进了书店数据库和客户代码之间功能的良好分隔。客户代码不知道书籍的存储方式和书店代码查找平装书的方式。书店代码也不知道找到平装书后将对平装书进行什么处理。 <div style="FONT-SIZE: 10pt"> <div style="FONT-SIZE: 10pt"> <img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">//?bookstore.cs<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">using?System;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">//此命名空间中的几个类用以维护书籍数据库:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">namespace?Bookstore?<img id="_75_1230_Open_Image" onclick="this.style.display='none'; document.getElementById('_75_1230_Open_Text').style.display='none'; document.getElementById('_75_1230_Closed_Image').style.display='inline'; document.getElementById('_75_1230_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954295.gif" align="top"><img id="_75_1230_Closed_Image" onclick="this.style.display='none'; document.getElementById('_75_1230_Closed_Text').style.display='none'; document.getElementById('_75_1230_Open_Image').style.display='inline'; document.getElementById('_75_1230_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954584.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???using?System.Collections;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???//?描述数据库中每一本书具有的属性:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???public?struct?Book<img id="_155_535_Open_Image" onclick="this.style.display='none'; document.getElementById('_155_535_Open_Text').style.display='none'; document.getElementById('_155_535_Closed_Image').style.display='inline'; document.getElementById('_155_535_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_155_535_Closed_Image" onclick="this.style.display='none'; document.getElementById('_155_535_Closed_Text').style.display='none'; document.getElementById('_155_535_Open_Image').style.display='inline'; document.getElementById('_155_535_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">???...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????public?string?Title;????????//?书的题目.<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????public?string?Author;???????//?书的作者.<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????public?decimal?Price;???????//?书的价格.<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????public?bool?Paperback;??????//?是不是平装书?<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????public?Book(string?title,?string?author,?decimal?price,?bool?paperBack)<img id="_416_530_Open_Image" onclick="this.style.display='none'; document.getElementById('_416_530_Open_Text').style.display='none'; document.getElementById('_416_530_Closed_Image').style.display='inline'; document.getElementById('_416_530_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_416_530_Closed_Image" onclick="this.style.display='none'; document.getElementById('_416_530_Closed_Text').style.display='none'; document.getElementById('_416_530_Open_Image').style.display='inline'; document.getElementById('_416_530_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">??????...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????Title?=?title;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????Author?=?author;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????Price?=?price;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????Paperback?=?paperBack;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">??????}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">???}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???//?为处理平装书的类声明一个委托类型（delegate类型）:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???public?delegate?void?ProcessBookDelegate(Book?book);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???//?维护书籍的数据库.<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???public?class?BookDB<img id="_673_1228_Open_Image" onclick="this.style.display='none'; document.getElementById('_673_1228_Open_Text').style.display='none'; document.getElementById('_673_1228_Closed_Image').style.display='inline'; document.getElementById('_673_1228_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_673_1228_Closed_Image" onclick="this.style.display='none'; document.getElementById('_673_1228_Closed_Text').style.display='none'; document.getElementById('_673_1228_Open_Image').style.display='inline'; document.getElementById('_673_1228_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">???...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????//?数据库中所有书籍的清单:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????ArrayList?list?=?new?ArrayList();???<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????//?向数据库中添加一本书:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????public?void?AddBook(string?title,?bool?paperBack)<img id="_854_924_Open_Image" onclick="this.style.display='none'; document.getElementById('_854_924_Open_Text').style.display='none'; document.getElementById('_854_924_Closed_Image').style.display='inline'; document.getElementById('_854_924_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_854_924_Closed_Image" onclick="this.style.display='none'; document.getElementById('_854_924_Closed_Text').style.display='none'; document.getElementById('_854_924_Open_Image').style.display='inline'; document.getElementById('_854_924_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">??????...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????list.Add(new?Book(title,?author,?price,?paperBack));<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">??????}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????//?对于每一本平装书调用ProcessBookDelegate这个委托，以对平装书进行处理:?<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????public?void?ProcessPaperbackBooks(ProcessBookDelegate?processBook)<img id="_1061_1223_Open_Image" onclick="this.style.display='none'; document.getElementById('_1061_1223_Open_Text').style.display='none'; document.getElementById('_1061_1223_Closed_Image').style.display='inline'; document.getElementById('_1061_1223_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1061_1223_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1061_1223_Closed_Text').style.display='none'; document.getElementById('_1061_1223_Open_Image').style.display='inline'; document.getElementById('_1061_1223_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">??????...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????foreach?(Book?b?in?list)?<img id="_1107_1215_Open_Image" onclick="this.style.display='none'; document.getElementById('_1107_1215_Open_Text').style.display='none'; document.getElementById('_1107_1215_Closed_Image').style.display='inline'; document.getElementById('_1107_1215_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1107_1215_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1107_1215_Closed_Text').style.display='none'; document.getElementById('_1107_1215_Open_Image').style.display='inline'; document.getElementById('_1107_1215_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">?????????...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">????????????if?(b.Paperback)<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">????????????//?Calling?the?delegate:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???????????????processBook(b);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">?????????}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">??????}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">???}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101955830.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">//?使用Bookstore命名空间里的类:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">namespace?BookTestClient<img id="_1281_3033_Open_Image" onclick="this.style.display='none'; document.getElementById('_1281_3033_Open_Text').style.display='none'; document.getElementById('_1281_3033_Closed_Image').style.display='inline'; document.getElementById('_1281_3033_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954295.gif" align="top"><img id="_1281_3033_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1281_3033_Closed_Text').style.display='none'; document.getElementById('_1281_3033_Open_Image').style.display='inline'; document.getElementById('_1281_3033_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954584.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???using?Bookstore;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???//?具有统计平装书并求出平装书的平均价格功能的类:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???class?PriceTotaller<img id="_1360_1644_Open_Image" onclick="this.style.display='none'; document.getElementById('_1360_1644_Open_Text').style.display='none'; document.getElementById('_1360_1644_Closed_Image').style.display='inline'; document.getElementById('_1360_1644_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1360_1644_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1360_1644_Closed_Text').style.display='none'; document.getElementById('_1360_1644_Open_Image').style.display='inline'; document.getElementById('_1360_1644_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">???...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????int?countBooks?=?0;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????decimal?priceBooks?=?0.0m;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????internal?void?AddBookToTotal(Book?book)<img id="_1474_1543_Open_Image" onclick="this.style.display='none'; document.getElementById('_1474_1543_Open_Text').style.display='none'; document.getElementById('_1474_1543_Closed_Image').style.display='inline'; document.getElementById('_1474_1543_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1474_1543_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1474_1543_Closed_Text').style.display='none'; document.getElementById('_1474_1543_Open_Image').style.display='inline'; document.getElementById('_1474_1543_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">??????...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????countBooks?+=?1;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????priceBooks?+=?book.Price;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">??????}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????internal?decimal?AveragePrice()<img id="_1590_1639_Open_Image" onclick="this.style.display='none'; document.getElementById('_1590_1639_Open_Text').style.display='none'; document.getElementById('_1590_1639_Closed_Image').style.display='inline'; document.getElementById('_1590_1639_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1590_1639_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1590_1639_Closed_Text').style.display='none'; document.getElementById('_1590_1639_Open_Image').style.display='inline'; document.getElementById('_1590_1639_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">??????...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????return?priceBooks?/?countBooks;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">??????}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">???}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???//?用以测试书籍数据库的类:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???class?Test<img id="_1683_3031_Open_Image" onclick="this.style.display='none'; document.getElementById('_1683_3031_Open_Text').style.display='none'; document.getElementById('_1683_3031_Closed_Image').style.display='inline'; document.getElementById('_1683_3031_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1683_3031_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1683_3031_Closed_Text').style.display='none'; document.getElementById('_1683_3031_Open_Image').style.display='inline'; document.getElementById('_1683_3031_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">???...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????//?打印书籍题目的静态方法.<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????static?void?PrintTitle(Book?b)<img id="_1750_1805_Open_Image" onclick="this.style.display='none'; document.getElementById('_1750_1805_Open_Text').style.display='none'; document.getElementById('_1750_1805_Closed_Image').style.display='inline'; document.getElementById('_1750_1805_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1750_1805_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1750_1805_Closed_Text').style.display='none'; document.getElementById('_1750_1805_Open_Image').style.display='inline'; document.getElementById('_1750_1805_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">??????...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????Console.WriteLine("???{0}",?b.Title);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">??????}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????//?程序执行的入口：<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????static?void?Main()<img id="_1857_2510_Open_Image" onclick="this.style.display='none'; document.getElementById('_1857_2510_Open_Text').style.display='none'; document.getElementById('_1857_2510_Closed_Image').style.display='inline'; document.getElementById('_1857_2510_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1857_2510_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1857_2510_Closed_Text').style.display='none'; document.getElementById('_1857_2510_Open_Image').style.display='inline'; document.getElementById('_1857_2510_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">??????...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????BookDB?bookDB?=?new?BookDB();<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????//?用几本书来输初始化书籍数据库:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????AddBooks(bookDB);??????<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????//?打印平装书的题目:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????Console.WriteLine("Paperback?Book?Titles:");<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???????????//?创建与静态方法?Test.PrintTitle?关联的新的委托对象:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???????????bookDB.ProcessPaperbackBooks(new?ProcessBookDelegate(PrintTitle));<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????//?通过PriceTotaller的实例获取平装书的平均价格:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????PriceTotaller?totaller?=?new?PriceTotaller();<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???????????//?创建与对象?totaller?上的非静态方法?AddBookToTotal?关联的新的委托对象:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">???????????bookDB.ProcessPaperbackBooks(new?ProcessBookDelegate(totaller.AddBookToTotal));<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????Console.WriteLine("平装书的平均价格:?${0:#.##}",<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">????????????totaller.AveragePrice());<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">??????}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????//?向数据库添加书以初始化书籍数据库:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">??????static?void?AddBooks(BookDB?bookDB)<img id="_2588_3026_Open_Image" onclick="this.style.display='none'; document.getElementById('_2588_3026_Open_Text').style.display='none'; document.getElementById('_2588_3026_Closed_Image').style.display='inline'; document.getElementById('_2588_3026_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_2588_3026_Closed_Image" onclick="this.style.display='none'; document.getElementById('_2588_3026_Closed_Text').style.display='none'; document.getElementById('_2588_3026_Open_Image').style.display='inline'; document.getElementById('_2588_3026_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">??????...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????bookDB.AddBook("The?C?Programming?Language",?<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">????????????"Brian?W.?Kernighan?and?Dennis?M.?Ritchie",?19.95m,?true);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????bookDB.AddBook("The?Unicode?Standard?2.0",?<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">????????????"The?Unicode?Consortium",?39.95m,?true);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????bookDB.AddBook("The?MS-DOS?Encyclopedia",?<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">????????????"Ray?Duncan",?129.95m,?false);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">?????????bookDB.AddBook("Dogbert's?Clues?for?the?Clueless",?<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">????????????"Scott?Adams",?12.00m,?true);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">??????}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">???}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101955830.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">输出：<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">Paperback?Book?Titles:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">???The?C?Programming?Language<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">???The?Unicode?Standard?2.0<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">???Dogbert's?Clues?for?the?Clueless<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">平装书的平均价格:?$23.97 ? 声明委托?? 以下语句：??? |