Skip to main content

What are ASP.NET Delegates, Types and Examples?


Delegate, Multicast Delegate and Generic Delegate

DelegateMulticast DelegateGeneric Delegate

Multiple Examples and Live Results

Single Delegates ExamplesMapped Delegate Static and Instance Methods
Multicast Delegate ExamplesWhat are Generic Delegates, Types and Examples
What is “Delegate”? What are different “Types” of Delegate? What is “Multicast Delegate”?What is “Generic Delegate”?

Delegate is an object which holds the references to a method within delegate object.
Delegate is a type-safe object.
Delegate is invoking to methods in asynchronously manner. 
Delegate encapsulates a static method or instance methods. 
Delegate can be with parameters or without parameters. 


Delegate’s benefits,
  1) Improve the performance of application. 
  2) Encapsulate to methods call from caller. 
  3) Call a method asynchronously.

Three steps for using Delegates,
  1) Declare
  2) Create 
  3) Point

Syntax: -   public delegate delegate_type delegate_name();
Types of Delegates,

  1) Delegate
A delegate is use when you need to pass to single reference to a method within delegate object. 
A multicast delegate is use when we needed to pass the more than one reference to a method within delegate object.


The basic examples of Delegates using in C# .Net as given below,

namespace delegateExample
{
    public delegate int AddByDelegate(int var1, int var2);

    public class DelegateClass
    {
        public static int Add(int a, int b)
        {
            return a + b;
        }
        static void Main(string[] args)
        {
            //Creating the Delegate Instance
            AddByDelegate delObject = new AddByDelegate(Add);

            Console.Write("Please enter value");
            int num1 = Int32.Parse(Console.ReadLine());
            int num2 = Int32.Parse(Console.ReadLine());

            // Here method Add is call.
            int Result = delObject(num1, num2);
            Console.WriteLine("Result :" + Result);
            Console.ReadLine();
        }
    }
}

//The Delegate - OutPut

Result : 30

Example for Multicast Delegate as following,

namespace MulticastDelegateExample
{
    public delegate int MulticastDelegateName(int num1, int num2);

    public class MulticastClass
    {

        public static int Add(int num1, int num2)
        {
            return num1 + num2;
        }

        public static int Sub(int num1, int num2)
        {
            return num1 - num2;
        }

        static void Main(string[] args)
        {
            //Create the Add Delegate Instance
            MulticastDelegateName objDelegt = new MulticastDelegateName(Add);
            
            Console.WriteLine("Please enter numbers!");

            int num1 = Int32.Parse(Console.ReadLine());
            int num2 = Int32.Parse(Console.ReadLine());

            int AddRest = objDelegt(num1, num2);
            Console.WriteLine("Result :" + AddRest);

            //Create the Sub Delegate Instance
            objDelegt += new MulticastDelegateName(Sub);
            int subRest = objDelegt(num1, num2);
            Console.WriteLine("Result :" + subRest);

            Console.ReadLine();
        }
    }
}

The Output as given below,

Please enter numbers!
num1 = 20
num2 = 10

Results: Add: 30 and Sub: 10


Microsoft provides three ready-made generics delegate. This is call shorter and sweeter delegate. This to minimize the code complexity of the apps.
1.      Func< input, output >
2.      Action< inputParameter >
3.      Predicate< inputParameter >

Func <input, output > Delegate:-

The Func <input, output> generic delegate is use, when you need to some input parameter and then return some output.

The example for Func generic delegate as given below,
namespace GenericDelegate
{
    public class Delegates
    {
        static void Main(string[] args)
        {
            // int is a input parameter and double is output parameter
            Func<intdouble> calPiR2Obj = r => 3.12 * r * r;
            Console.Write(calPiR2Obj(4));
            Console.ReadLine();
        }
    }
}

Action< inputParameter > Delegate:-

The Action< inputParameter> generics delegate is use, when you need to input parameter and no need to return output that means return void.

The example for Action generics delegate as below,
namespace GenericDelegate
{
    public class Delegates
    {
        static void Main(string[] args)
        {
            Action<string> ActionObject = x => Console.WriteLine(x);
            ActionObject("This is Action delegate!");

            Console.ReadLine();
        }
    }
}

Predicate < inputParameter > Delegate:-

The Predicate generics delegate is use, when you need to input parameter and return output.
The return output is Boolean type just like true or false. This delegate is uses when you need to check the conditional statements are true or false. 

The example for Predicate delegate as below,
namespace GenericDelegate
{
    public class Delegates
    {
        static void Main(string[] args)
        {
            // string is input but out put is retun True or False
            Predicate<string> checkConditionIsTF = x => x.Length > 10;
            Console.WriteLine(checkConditionIsTF("Anil Kumar Singh"));
            Console.ReadLine();
        }
    }
}


The example for Generic Delegates:-

namespace GenericDelegate
{   
    public class Delegates
    {
        static void Main(string[] args)
        {
            //Int is an input parameter and double is output parameter.
            Func<intdouble > calPiR2Obj = r => 3.12 * r * r;
            Console.WriteLine(calPiR2Obj(4));

            //String is input but no output return.
            Action<string > ActionObject = x => Console.WriteLine(x);
            ActionObject("This is Action delegate!");

            //String is input but output, the return is true or false
            Predicatestring > checkConditionIsTF = x => x.Length > 10;
            Console.WriteLine(checkConditionIsTF("Anil Kumar Singh"));

            Console.ReadLine();
        }
    }
}

I hope you are enjoying with this post! Please share with you friends. Thank you!!!
By Anil Singh | Rating of this article (*****)

Popular posts from this blog

nullinjectorerror no provider for httpclient angular 17

In Angular 17 where the standalone true option is set by default, the app.config.ts file is generated in src/app/ and provideHttpClient(). We can be added to the list of providers in app.config.ts Step 1:   To provide HttpClient in a standalone app we could do this in the app.config.ts file, app.config.ts: import { ApplicationConfig } from '@angular/core'; import { provideRouter } from '@angular/router'; import { routes } from './app.routes'; import { provideClientHydration } from '@angular/platform-browser'; //This (provideHttpClient) will help us to resolve the issue  import {provideHttpClient} from '@angular/common/http'; export const appConfig: ApplicationConfig = {   providers: [ provideRouter(routes),  provideClientHydration(), provideHttpClient ()      ] }; The appConfig const is used in the main.ts file, see the code, main.ts : import { bootstrapApplication } from '@angular/platform-browser'; import { appConfig } from '

39 Best Object Oriented JavaScript Interview Questions and Answers

Most Popular 37 Key Questions for JavaScript Interviews. What is Object in JavaScript? What is the Prototype object in JavaScript and how it is used? What is "this"? What is its value? Explain why "self" is needed instead of "this". What is a Closure and why are they so useful to us? Explain how to write class methods vs. instance methods. Can you explain the difference between == and ===? Can you explain the difference between call and apply? Explain why Asynchronous code is important in JavaScript? Can you please tell me a story about JavaScript performance problems? Tell me your JavaScript Naming Convention? How do you define a class and its constructor? What is Hoisted in JavaScript? What is function overloadin

List of Countries, Nationalities and their Code In Excel File

Download JSON file for this List - Click on JSON file    Countries List, Nationalities and Code Excel ID Country Country Code Nationality Person 1 UNITED KINGDOM GB British a Briton 2 ARGENTINA AR Argentinian an Argentinian 3 AUSTRALIA AU Australian an Australian 4 BAHAMAS BS Bahamian a Bahamian 5 BELGIUM BE Belgian a Belgian 6 BRAZIL BR Brazilian a Brazilian 7 CANADA CA Canadian a Canadian 8 CHINA CN Chinese a Chinese 9 COLOMBIA CO Colombian a Colombian 10 CUBA CU Cuban a Cuban 11 DOMINICAN REPUBLIC DO Dominican a Dominican 12 ECUADOR EC Ecuadorean an Ecuadorean 13 EL SALVADOR

25 Best Vue.js 2 Interview Questions and Answers

What Is Vue.js? The Vue.js is a progressive JavaScript framework and used to building the interactive user interfaces and also it’s focused on the view layer only (front end). The Vue.js is easy to integrate with other libraries and others existing projects. Vue.js is very popular for Single Page Applications developments. The Vue.js is lighter, smaller in size and so faster. It also supports the MVVM ( Model-View-ViewModel ) pattern. The Vue.js is supporting to multiple Components and libraries like - ü   Tables and data grids ü   Notifications ü   Loader ü   Calendar ü   Display time, date and age ü   Progress Bar ü   Tooltip ü   Overlay ü   Icons ü   Menu ü   Charts ü   Map ü   Pdf viewer ü   And so on The Vue.js was developed by “ Evan You ”, an Ex Google software engineer. The latest version is Vue.js 2. The Vue.js 2 is very similar to Angular because Evan You was inspired by Angular and the Vue.js 2 components looks like -

Groovy Interview Questions and Answers

What Is Groovy? Groovy is fully object oriented programming language for JVM - Java Virtual Machines and used to combine Java modules, to write Java application and to extend existing Java application. Groovy is a powerful high level language for the Java platform which compiles down to Java byte-code. Groovy is Java syntax compatible and is from Apache family of software. Why You Use Groovy? Groovy has a rich stock of Java Libraries and easily integrate with your existing infrastructure like – 1.       Servlet Containers 2.       App Servers 3.       Loads of databases with JDBC drivers 4.       Completely Object Oriented Groovy can be used both as a programming language and as a scripting language. It has efficient object navigation, Literal declaration for maps, arrays, ranges and regular expressions, and Operators can be overloaded. What are the Dependencies for Groovy? Java 1.4 plus and the Groovy jar, it also depend on the ASM library at run-tim