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Event in ASP.Net c#

When users perform any types of activities like Mouse over, Mouse clicks, Keyboard presses etc that means events is generated.

Events are members of class, when something happening to provide notifications to clients of that class and raise event and have the message about the events and send to the application and application is responsible and handle this event using event handlers.

Event handler is a method that has the same signature as the event and this method is executed when the event occurs.

Event keyword is used to create an instance of an event that can store methods in its invocations.

Event is declared using delegates.

If you define an event you need first to define a delegate that contains the methods that will be called when the event raised, and then you define the event based on that delegate.
This is done using to the += and -= operators.


when you want to register an event handler with an event you click on a button (button1_Click) i.e.
this.button1.click += new System.EventHandler(this.button1_Click);

Example for Events as given below.

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

namespace ConsoleApplication2events
{
    public delegate void EventHandler();
    public class Program
    {
        public static event EventHandler _CallEvent;
        static void Main()
        {
            // Add event handlers to Show event.
            _CallEvent += new EventHandler(Mouse);
            _CallEvent += new EventHandler(Button);

            // Invoke the event.
            _CallEvent.Invoke();

            Console.Read();
        }
        static void Mouse()
        {
            Console.WriteLine("Call to Mouse");
        }
        static void Button()
        {
            Console.WriteLine("Call to button");
        }
   }
}

The Output as given below

Call to Mouse
Call to button
===========================================

Another Example for Events

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

namespace EventHandlers
{
    public class HandlerClass
    {
        public delegate void TickHandler(HandlerClass m, EventArgs e);
        public event TickHandler Ticks;
        public EventArgs e = null;
       
        public void Start()
        {
            while (true)
            {
                Thread.Sleep(5000);
                if (Ticks != null)
                {
                    Ticks(this, e);
                }
            }
        }
    }
    public class callToHandler
    {
        public void TickEvent(HandlerClass m)
        {
            m.Ticks += new HandlerClass.TickHandler(ShowMsg);
        }
        private void ShowMsg(HandlerClass m, EventArgs e)
        {
            Console.WriteLine("This is show msg.");
        }
    }

    public class TestClass
    {
        static void Main()
        {
            HandlerClass Handler = new HandlerClass();
            callToHandler callHandler = new callToHandler();
            callHandler.TickEvent(Handler);
            Handler.Start();
        }
    }
}          


The Output as given below
               
This is show msg. (This msg call after 5 second b/c  here sleep commend is call for 5 second).


By Anil Singh | Rating of this article (*****)

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