Delegate (Delegate) and events (event) in. net:c#

delegates and events are widely used in the. Net framework, however, a good understanding of delegates and events is not easy for many people who are not in touch with C # for a long time. They are like a sill, after the threshold of the people, it is very easy, and no past people every time to see the Commission and events feel in the heart to panic, uncomfortable. In this article, I'll go through two examples of what is a delegate, why I use delegates, the origins of events, the meanings of delegates and events in the. Net framework, delegates, and events to the observer design pattern, and also a discussion of their intermediate code.  P1: What is a delegate? Is the event a delegate? A: A delegate can take a method as a parameter into another method. It can also be easily understood as a reference to a function. Yes, a special kind of delegate.   2. What are the actual applications of the consignment?

I'll give you two examples.

1,[3A] Greetings in different languages.

2,[3B] The Chinese version of QQ and Tencent QQ (International version of QQ) user personal Information "gender" presentation.

3, two delegate (Delegate) instance parsing.

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingsystem.web;/// <summary>///Language Class/// </summary>namespacegyg.de.models{ Public classLanguage {/// <summary>        ///declaring a delegate/// </summary>        /// <param name= "name" ></param>         Public Delegate stringGrateingdelegate (stringname); /// <summary>        ///Chinese Greetings/// </summary>        /// <param name= "name" ></param>        /// <returns></returns>         Public Static stringEnggrateing (stringname) {            return "English name ="+name; }        /// <summary>        ///British Greetings/// </summary>        /// <param name= "name" ></param>        /// <returns></returns>         Public Static stringChinagreateing (stringname) {            return "Chinese name ="+name; }         Public Static stringGreateperpon (stringname, Grateingdelegate grateperpon) {            returngrateperpon (name); }    }}

Case 2:

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingsystem.web;namespacegyg.de.models{ Public classSex { Public Delegate stringSexdalegate (stringSexcode);  Public Static stringChinasex (stringSexcode) {            Switch(sexcode) { Case "0":                    return "male";  Case "1":                    return "female"; default:                    return "Unknown"; }        }         Public Static stringEngsex (stringSexcode) {            Switch(sexcode) { Case "0":                    return "Girl";  Case "1":                    return " Boy"; default:                    return "Unknown"; }        }         Public Static stringSexconvert (stringSexcode, Sexdalegate Sexconvert) {            returnSexconvert (Sexcode); }    }}

Controller code:

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingsystem.web;usingSYSTEM.WEB.MVC;usingGyg.DE.Models;namespacegyg.de.controllers{ Public classPerponcontroller:controller {//Get:perpon         PublicActionResult Index () {stringName = Language.greateperpon ("gu Peony", language.chinagreateing); stringNameeng = Language.greateperpon ("Gyg", language.enggrateing); viewdata["name"] =name; viewdata["Nameeng"] =Nameeng; returnView (); }         PublicActionResult sextest () {viewdata["Chinasex"] = Sex.sexconvert ("0", Sex.chinasex); viewdata["Engsex"] = Sex.sexconvert ("1", Sex.engsex); returnView (); }    }}

Page code:

@{Layout=NULL;}<! DOCTYPE html>"Viewport"Content="Width=device-width"/> <title>Index</title>@ViewData ["name"] <br/>@ViewData ["Nameeng"] <br/> <a href="/perpon/sextest">SexTest</a> </div></body>
@{Layout=NULL;}<! DOCTYPE html>"Viewport"Content="Width=device-width"/> <title>SexTest</title>@ViewData ["Chinasex"] <br/>@ViewData ["Engsex"] <br/> <a href="/perpon/index">Index</a> </div></body>
4  . What are the benefits of using a delegate (Delegate)? 
We now make a summary of the Commission:
　　A delegate is a class that defines a method's type so that it can be passed as a parameter to another method, which dynamically assigns the method to the parameter, avoids the large use of the If-else (Switch) statement in the program, and makes the program more extensible.
Delegate (Delegate) and events (event) in. net:c#