Delegate, Method as Parameter.

1. An agent that takes a method as a parameter to another method. A function pointer similar to C.
   

   usingSystem;usingSystem.Windows.Forms;usingSystem.Threading;namespacedemo{ Public Delegate voidGreeting (stringname);  Public classDemo {Private Static voidGreetingenglish (stringname) {Console.WriteLine ("hello,{0}", name); }        Private Static voidGreetingchinese (stringname) {Console.WriteLine ("hello, {0}", name); }        //A delegate that takes a method as a parameter to another method. A delegate can represent a sequence of return values and parameter types that are consistent with their methods.        Private Static voidGreetingpeople (stringname, greeting greet)        {greet (name); }                     Public Static voidMain () {greetingpeople ("Jeffrey Richter", Greetingenglish); Greetingpeople ("Andy Lau", Greetingchinese);        Console.readkey (); }    }}

2. To bind a method to a delegate
   

   usingSystem;usingSystem.Threading;namespacedemo{ Public Delegate voidGreeting (stringname);  Public classDemo {Private Static voidGreetingenglish (stringname) {Console.WriteLine ("hello,{0}", name); }        Private Static voidGreetingchinese (stringname) {Console.WriteLine ("hello, {0}", name); }        Private Static voidGreetingfrance (stringnom) {Console.WriteLine ("bonjour,{0}", nom); }        //Delegate:use the Method name as Parameters.        Private Static voidGreetingpeople (stringname, greeting greet)        {greet (name); }                     Public Static voidMain () {greetingpeople ("Jeffrey Richter", Greetingenglish); Greetingpeople ("Andy Lau", Greetingchinese); //bind Method to DelegateGreeting Chinese = Greetingchinese; Greeting 中文版= Greetingenglish; 中文版+ = greetingfrance; Chinese ("Xu Ming will"); 中文版 ("Matt Petrek");        Console.readkey (); }    }}

3. Delegates and interfaces
   

   usingSystem;usingSystem.Threading;namespacedemo{Interfaceigreeting{voidGreeting (stringname);    };  Public classgreetingchinese:igreeting { Public voidGreeting (stringname) {Console.WriteLine ("hello, {0}", name); }    }         Public classgreetingenglish:igreeting { Public voidGreeting (stringname) {Console.WriteLine ("hello,{0}", name); }    }     Public classDemo {Private Static void Greeting(stringname, igreeting greeting) {Greeting.        Greeting (name); }         Public Static voidMain () {igreeting Chinese=NewGreetingchinese (); Igreeting 中文版=NewGreetingenglish (); Chinese. Greeting (  " Xu Ming " ); 中文版. Greeting ("Jeffrey Richter" ); Greeting ("Matt Petrik"  , 中文版);        Console.readkey (); }    }}

4. Better encapsulation, the origin of the event
   

   usingSystem;usingSystem.Threading;namespacedemo{ Public Delegate void Greet(stringname);  Public classGreetingmanager { PublicGreet Delegreet;  Public voidGreeting (stringname, Greet Greet)        {greet (name); }    }     Public classDemo {Private Static voidGreetingenglish (stringname) {Console.WriteLine ("hello,{0}", name); }        Private Static voidGreetingchinese (stringname) {Console.WriteLine ("hello, {0}", name); }        //Main ()         Public Static voidMain () {greetingmanager gm=NewGreetingmanager (); Gm.delegreet = Greetingchinese; Gm.delegreet + = Greetingenglish; gm. Greeting ("Matt Petrik"  , gm.delegreet);        Console.readkey (); }    }}

5. Better encapsulation, ready to introduce events
   

   usingSystem;usingSystem.Threading;namespacedemo{ Public Delegate voidGreet (stringname);  Public classGreetingmanager { PublicGreet Delegreet;  Public voidGreeting (stringname) {            if(delegreet!=NULL) {delegreet (name); }        }    }     Public classDemo {Private Static voidGreetingenglish (stringname) {Console.WriteLine ("hello,{0}", name); }        Private Static voidGreetingchinese (stringname) {Console.WriteLine ("hello, {0}", name); }        //Main ()         Public Static voidMain () {greetingmanager gm=NewGreetingmanager (); Gm.delegreet=Greetingchinese; Gm.delegreet+=Greetingenglish; gm. Greeting ("Matt Petrik");        Console.readkey (); }    }}

6. The purpose of the delegate is to expose it to the outside to allow the client to register the method. The event guarantee is always private within the class and can be considered a property that is customized for delegate.
   

   usingSystem;usingSystem.Threading;namespacedemo{ Public Delegate voidGreet (stringname);  Public classGreetingmanager {//Public Greet Delegreet;         Public EventGreet Eventgreet;  Public voidGreeting (stringname) {            if(eventgreet!=NULL) Eventgreet (name); }    }     Public classDemo {Private Static voidGreetingenglish (stringname) {Console.WriteLine ("hello,{0}", name); }        Private Static voidGreetingchinese (stringname) {Console.WriteLine ("hello, {0}", name); }        //Main ()         Public Static voidMain () {greetingmanager gm=NewGreetingmanager (); gm. Eventgreet+=Greetingchinese; gm. Eventgreet+=Greetingenglish; //greeting call from client, that 's not good!gm. Greeting ("Matt Petrik");        Console.readkey (); }    }}

8. . NET Framework for delegates and events
   Of
   

Delegate, Method as Parameter.