Used of Delegates in .Net

Question

Possible Duplicate:
The purpose of delegates

What is actual use of Delegate in .Net

Answer 1

A delegate in C# allows you to call a group of methods that are specified at runtime instead of one method that is specified at compile-time. Events in the system are handled using delegates because that allows them to raise one event and call a whole slew of methods specified by the different listeners that have subscribed to the event.

public class EventRaiser
{
    public delegate void SomethingHappened();

    public SomethingHappend OnSomethingHappened
    { get; set; }
}

public class Listener
{
    public void DoSomething()
    {
        //Do something
    }
}

public class OtherListener
{
    public void DoSomethingDifferent()
    {
        //Do something different
    }
}

EventRaiser raiser = new EventRaiser();
Listener listener = new Listener();
OtherListener other = new OtherListener();

raiser.OnSomethingHappened += listener.DoSomething;
raiser.OnSomethingHappened += other.DoSomethingDifferent;

//This call will call both DoSomething and DoSomethingDifferent
raiser.OnSomethingHappened();