C# Multicast Delegates Tutorial with Programming Example

In this chapter you will learn:

• What is multicast delegate?
• How to initialize c# multicast delegates?
• Programming Example

What is Multicast Delegate?

Multicast Delegate is an extension of normal delegates. It combines more than one method at a single moment of time.

Important Fact about Multicast Delegate

1. In Multicasting, Delegates can be combined and when you call a delegate, a whole list of methods is called.
2. All methods are called in FIFO (First in First Out) order.
3. + or += Operator is used for adding methods to delegates.
4. – or -= Operator is used for removing methods from the delegates list.

Programming Example

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Multicast_Delegates
{    
    class TestDeleGate
    {
        public delegate void ShowMessage(string s);
        public void message1(string msg)
        {
            Console.WriteLine("1st Message is : {0}", msg);
        }
        public void message2(string msg)
        {
            Console.WriteLine("2nd Message is : {0}", msg);
        }
        public void message3(string msg)
        {
            Console.WriteLine("3rd Message is : {0}", msg);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            TestDeleGate td = new TestDeleGate();
            TestDeleGate.ShowMessage message = null;
            message += new TestDeleGate.ShowMessage(td.message1);
            message += new TestDeleGate.ShowMessage(td.message2);
            message += new TestDeleGate.ShowMessage(td.message3);
            message("Hello Multicast Delegates");
            message -= new TestDeleGate.ShowMessage(td.message2);
            Console.WriteLine("----------------------");
            message("Message 2 Removed");
            Console.ReadKey();
        }
    }
}

1st Message is : Hello Multicast Delegates

2nd Message is : Hello Multicast Delegates

3rd Message is : Hello Multicast Delegates

----------------------

1st Message is : Message 2 Removed

3rd Message is : Message 2 Removed

Explanation

This is the very basic example of Multicast delegates.

1. Delegates Created

   public delegate void ShowMessage(string s);

   
   
2. Created 3 functions

   public void message1(string msg)
   public void message2(string msg)
   public void message3(string msg)

   
   
3. Created Delegate's Object in Main method

   TestDeleGate.ShowMessage message = null;

   
   
4. All the methods are added to delegates object.

   message += new TestDeleGate.ShowMessage(td.message1);
          message += new TestDeleGate.ShowMessage(td.message2);
   message += new TestDeleGate.ShowMessage(td.message3);

   
   Print Delegates

   message("Hello Multicast Delegates");

   
   
5. Remove message2(string msg) from delegates

   message -= new TestDeleGate.ShowMessage(td.message2);

   
   

Summary

In this chapter you learned about multicast delegates in c#. In the next chapter you will learn very important topics in c# - Event Handling.