Delegates

Delegates

This were pointer to Methods whenever we call a method to execute a method it creates a stack and destroys .Each time the method is called a stack is created and destroyed.

If u wants to call a method for multiple times without multiple stacks getting created and destroyed make use of a “Delegate”.

Is a type which holds the method(s) reference in an object?

It is also referred as type safe function.       Type safe means same parameter type and same return type

Advantages

Used to call a method asynchronously.

Effective use of delegates approves the performance of application.

Declaration

Syntax:

Public delegate type of delegate, delegatename ()

Eg:

Public delegate int mydelegate(int delvar1,int delvar2)

Delegates:

Public void Add(int x, int y)

{

Console.WriteLine(x+y);

}

Public delegate void AddDel(int x, int y)

Public string SayHello(string name)

{

return “Hello” +name;

}

Public delegate string sayDel(string str)

Creating objects of Delegates

AddDel ad=new AddDel(Add);

sayDel sd=new sayDel(SayHello);

Delegates are of two types

Single cast delegates

Multi cast delegates

Single cast delegate:

If a delegate is used for calling only a single method than it is known as single cast delegate.

output

Multi cast Delegate

If a delegate is used for calling more than one method than it is called as Multi Cast Delegate.

If you want to add a method to the invocation list  of a delegate object, you simple make use of the overloaded+=operator and if you want to remove a method from invocation list make use of overloaded –

Note:

If you want to create a multi cast delegate with return type you will get the return type of the last method in the invocation list.