Explain Delegates step by step.

In this C# presentation will discuss about a concept called Delegates.

1. DELEGATES This presentation will explain about delegates in C#( Csharp ).

2. Delegate is defined as a pointer to a function . A delegate is an object that can refer to a method . Therefore , when you create a delegate ,you are creating an object that can hold a reference to a method . The delegate declaration specifies a return type and parameter list.

3. A delegate can invoke the method to which it refers. Thus, the method that will be invoked by a delegate is not determined at compile time , but rather at runtime. This is the advantage of a delegate . You can then initialize the variable as a reference to any function that has the same return type and parameter list as that delegate . Delegate is a communication channel, it helps us to call back after getting the results.

4. The general form of delegate declaration is shown here:- Syntax : public delegate ret-type delegatename (parameter-list ); ret-type is the type of value returned by the methods that the delegate will be calling. The name of the delegate is specified by name . The parameters required by the methods called through the delegates are specified in the parameter-list.

5. Uses of delegates :- Delegates allow methods to be passed as parameters . Delegates can be used to define call back methods . Delegates are used to pass methods as arguments to other methods . Delegates are like function pointers where input parameter and return parameter should be same type.

6. Program :- using System;  namespace ConsoleApplication1  {    public delegate int myDel ( int a, int b)    class Program    {      static void MethodAdd ( int a, int b)       {          int c= a+b ;          return c;        }     static void Main(string[] args )     {        myDel obj = new myDel ( MethodAdd );        int c= obj (10,6)        Console.Writeline (“addition of two no. is: “ +c);         Console.ReadKey ();      }  }  }

7. Output:- addition of two no. is: 16 Types of Delegates : There are two types of delegate . 1. Single delegate:- A delegate is called simple delegate if it invokes a single method . Simple delegate refer to a single method.

8. 2. Multicast delegate:- The Multicast delegates can invoke multiple methods . Multicast delegates can send messages to multiple clients/subscribers It uses += sign to broadcast multiple clients . It makes two way communication.

9. Program :- using System;  namespace ConsoleApplication2  {    public delegate int myDel ( int a, int b)    class Program    {      static void MethodAdd ( int a, int b)       {          Console.Writeline (“The sum is: “ + ( a+b ));        }       static void MethodMul ( int a, int b)       {          Console.Writeline (“The product is: “ + (a*b) );         }     static void Main(string[] args )     {        myDel obj = new myDel ( MethodAdd );        obj += new myDel ( MethodMul );                Console.ReadKey ();      }  }  }