What is Delegates and how to create it in c#?

The dictionary meaning of delegate is a person acting for another person. In c# it really means method acting for another method.

Definition of delegate:-

 A delegate is a class type object that contains the details of a method rather than data. It used to invoke a method that has been encapsulated into it at the time of its creation. Delegate in  c# are used for two purposes.

An important feature of a delegate is that it can be used to hold reference to a method to any class. The only requirement is that its signature must match the signature of the method.

1-Call back

2- Event handling

For creating and using delegates involve four steps:-

1-Delegate declaration

2-Delegate instantiation

3-Delegate methods definition

4-Delegate invocation

Modifiers

Four modifiers of the delegate type:

Public

Private

Protected

Internal

Example of delegate:-

//delegate declaration

Delegate voin Sanjibdelegate();

Class A

{

//instance delegate method

Public void DispalyA()

{

Console.writeline(“Display A”);

}

}

Class B

{

//static delegate method

Static public void DisplayB()

{

Console.writeline(“Display B”);

}

}

//delegate instance

A  mya  = new A();

Sanjibdelegate san = new Sanjibdelegate(mya.DisplayA);

//static method call here direct with class name.

Sanjibdelegate del = new Sanjibdelegate(B.DisplayB);

What are Multicast delegates:-

Multicast delegate is a method that holds and invokes multiple methods. It also called as combinable delegates.

 It must satisfy the following conditions:

1-The return type of the delegate must be void.

2-None of the parameters of the delegate type can e declared as output parameters, using out keyword.