C# 中的delegate

悠悠 2022-01-06 05:03 236阅读 0赞

刚开始，见了多次，但是从来没有理解，一大早过来就先google一下，先把这个问题搞清楚。

> delegate 的字面意思  
> vt. 委派…为代表  
> n. 代表

msdn上的解释  
A **delegate** declaration defines a reference type that can be used to encapsulate a method with a specific signature. A delegate instance encapsulates a static or an instance method. Delegates are roughly similar to function pointers in C++; however, delegates are type-safe and secure.

delegate声明一种引用类型，用来封装有特定签名的方法，可以是一个静态的方法或是实例的方法。类似于C++中的方法指针。

声明格式

>     [attributes] [modifiers] delegate result-type identifier ([formal-parameters]);

范例一

// keyword_delegate.cs
    // delegate declaration
    delegate void MyDelegate(int i);
    
    class Program
    {
       public static void Main()
       {
          TakesADelegate(new MyDelegate(DelegateFunction));
       }
    
       public static void TakesADelegate(MyDelegate SomeFunction)
       {
          SomeFunction(21);
       }
       
       public static void DelegateFunction(int i)
       {
          System.Console.WriteLine("Called by delegate with number: {0}.", i);
       }
    }

范例二

1 //  keyword\_delegate2.cs  
  2  //  Calling both static and instance methods from delegates   
  3  using  System;  
  4   
  5  //  delegate declaration   
  6  delegate  void  MyDelegate();  
  7   
  8  public  class  MyClass  
  9 \{  
 10  public  void  InstanceMethod()  
 11  \{  
 12  Console.WriteLine( " A message from the instance method. " );  
 13  \}  
 14   
 15  static  public  void  StaticMethod()  
 16  \{  
 17  Console.WriteLine( " A message from the static method. " );  
 18  \}  
 19 \}  
 20   
 21  public  class  MainClass  
 22 \{  
 23  static  public  void  Main()  
 24  \{  
 25  MyClass p  =  new  MyClass();  
 26   
 27  //  Map the delegate to the instance method:   
 28   MyDelegate d  =  new  MyDelegate(p.InstanceMethod);  
 29  d();  
 30   
 31  //  Map to the static method:   
 32   d  =  new  MyDelegate(MyClass.StaticMethod);  
 33  d();  
 34  \}  
 35 \}

本文中的大部分内容摘自http://msdn.microsoft.com/zh-cn/library/900fyy8e%28v=VS.71%29.aspx

转载于:https://www.cnblogs.com/mt4us/archive/2011/04/29/2032398.html