C# Extension Methods

最新推荐文章于 2025-08-22 21:23:47 发布

转载最新推荐文章于 2025-08-22 21:23:47 发布 · 86 阅读

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原文链接：http://www.cnblogs.com/Dylan-Java-NYC/p/5958925.html

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#c#

本文详细介绍了C#中的扩展方法，包括如何定义扩展方法、使用静态类包含这些方法以及如何调用它们。通过实例展示了将现有类的功能进行扩展而不必创建新的派生类的方法。

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In C#, extension methods enable you to add methods to existing class without creating a new derived class.

Extension methods 要求：

Define a static class to contain extension method. This class must be visible to client code.
Implement the extension method like a static method, but add "this" modifier before the first parameter.
The first parameter specifies the type that this extension method operates on.

 1 using System.Globalization;
 2 using System.Threading;
 3 
 4 namespace Library
 5 {
 6     public static class StringExtensions
 7     {
 8         //static method
 9         //public static string ConvertToTitleCase(this string source)
10         //extension method
11         public static string ConvertToTitleCase(this string source)
12         {
13             CultureInfo cultureInfo = Thread.CurrentThread.CurrentCulture;
14             TextInfo textInfo = cultureInfo.TextInfo;
15 
16             return textInfo.ToTitleCase(source);
17         }
18     }
19 }

Extension methods call:

Call extension method like extension method is an instance method on the type.

 1 namespace Library_Simple
 2 {
 3     //Import extension method namespace
 4     using Library;
 5     class Program
 6     {
 7         static void Main(String[] args)
 8         {
 9             string source = "the return of the king";
10             string extected = "The Return Of The King";
11 
12             //static method
13             //string result = StringExtensions.ConvertToTitleCase(source);
14             //extension method
15             string result = source.ConvertToTitleCase();
16 
17             Assert.IsNotNull(result);
18             Assert.AreEqual(expected, result);
19         }
20     }
21 }