Delegate and event on button click event in window form C#

Question

1.44/5 (2 votes)

See more:

Hello,

Can any body give me a simple example of delegate and event on click button event in window form C#. like if i click on button event which is configure on click button will fire.

C#

using System;
using System.Windows.Forms;

namespace WindowsFormsApplication21
{
    public partial class Form1 : Form
    {
        public delegate void BoilerLogHandler(string status);
        public event BoilerLogHandler BoilerEventLog;
	public Form1()
	{
	    InitializeComponent();

	}

	private void button1_Click(object sender, EventArgs e)
	{
	    MessageBox.Show("Dot Net Perls says hello.",
		"How is your day going?");
	}
    }
}

Thanks

What I have tried:

how to fire delegate and event on button click event in window form c#

Posted 8-May-16 19:10pm

Member 12131277

Updated 8-May-16 19:43pm

Add a Solution

Comments

Sergey Alexandrovich Kryukov 9-May-16 1:14am

The question makes no sense. You don't "fire" event, the System.Windows.Forms library does. You can only handle the even; and, for this purpose, you supply a delegate instance. It means inversion of control.

There is no a way to invoke this event at all, even if you create a derived class; this is the important .NET fool-proof feature. You can only invoke the event you declare yourself in your own class/struct.

—SA

Member 12131277 9-May-16 1:17am

ok...can you give me a example. how invoke control?
it is possible you expalain with a simple example

Sergey Alexandrovich Kryukov 9-May-16 1:25am

Wrong question. You don't need any examples at this moment. And you should not learn anything based on examples.
How can you understand any of them if you use the words "invoke control"? there is no such thing...
—SA

Member 15416709 2-Nov-21 17:28pm

A simple no would have sufficed. People like you really make new programmers lose interest on keep learning. Go eat a snickers man.

3 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Answer 1 · 2016-05-08T19:43:00

It possible you mean something like this:

C#

private delegate void BoilerLogHandler(string status);
BoilerLogHandler theDelegate = BoilerLogHandlerB;
private void myCheckBox_CheckedChanged(object sender, EventArgs e)
    {
    if (myCheckBox.Checked)
        {
        theDelegate = BoilerLogHandlerA;
        }
    else
        {
        theDelegate = BoilerLogHandlerB;
        }
    }

private void myButton_Click(object sender, EventArgs e)
    {
    theDelegate("Hello from a button click!");
    }
private static void BoilerLogHandlerA(string status)
    {
    Console.WriteLine("A: {0}", status);
    }
private static void BoilerLogHandlerB(string status)
    {
    Console.WriteLine("B: {0}", status);
    }

When you change the status of the checkbox, it changes the delegate. And when you click the button, the delegate is used to call whichever method is currently set.
For an event it's slightly different:

C#

/// <summary>
/// Event to indicate Test Event Thrown
/// </summary>
public event EventHandler TestEvent;
/// <summary>
/// Called to signal to subscribers that Test Event Thrown
/// </summary>
/// <param name="e"></param>
protected virtual void OnTestEvent(EventArgs e)
    {
    EventHandler eh = TestEvent;
    if (eh != null)
        {
        eh(this, e);
        }
    }
private void myCheckBox_CheckedChanged(object sender, EventArgs e)
    {
    if (myCheckBox.Checked)
        {
        TestEvent +=frmMain_TestEventA;
        }
    else
        {
        TestEvent += frmMain_TestEventB;
        }
    }

void frmMain_TestEventA(object sender, EventArgs e)
    {
    Console.WriteLine("EventA");
    }

void frmMain_TestEventB(object sender, EventArgs e)
    {
    Console.WriteLine("EventB");
    }

private void myButton_Click(object sender, EventArgs e)
    {
    OnTestEvent(new EventArgs());
    }

Now each time you change the CheckBox, another handler is added to the event.
Since an event is internally implemented via a delegate, you can also use the "+=" syntax with delegates to "chain" methods into it, but that's a little more rare to do directly.

Hrishikesh Ranjit Shivacharan · Answer 2 · 2016-05-08T20:32:00

How to Use Delegate -

C#

public delegate void PalashDelegate();

        class TestExpDelegate
        {
            public static void MyFunc()
            {
                Console.WriteLine("I was called by delegate ...");
            }

            public static void Main()
            {
                // Instantiation
                PalashDelegate PalashDelegate = new PalashDelegate(MyFunc);

                // Invocation
                PalashDelegate();
            }
        }

How to use Event -

C#

class TestExpEvent
{
   public event EventHandler chwEventFire_click;

   TestExpEvent()
   {                
       this.chwEventFire_click += new EventHandler(Obj_chwEventFire_click);
       this.chwEventFire_click += new EventHandler(Obj_chwEventFire_click);
       Console.Write("Constructor");
   }

   private void Button_Click(object sender, RoutedEventArgs e)
   {
       if (chwEventFire_click != null)
       {
           chwEventFire_click(this, new EventArgs());
       }
    }
       
    void Obj_chwEventFire_click(object sender, EventArgs e)
    {
       Console.Write("Event fire");
    }   
            
}

You can refer this link also.

Chapter 17. Delegates and Events[^]

Sergey Alexandrovich Kryukov · Answer 3 · 2016-05-08T19:23:00

Sorry, no code for you, because the question makes no sense. It does not mean that doing what you ask is possible or impossible; it's just because you are using non-existing or incorrectly understood concepts. Please see my comment to the question.

You really need to understand how event-oriented programming works. This is something to start with:
Inversion of control — Wikipedia, the free encyclopedia[^],
Event-driven programming — Wikipedia, the free encyclopedia[^],
Delegates (C# Programming Guide)[^],
Delegates Tutorial (C#)[^],
Events Tutorial (C#)[^],
Handling and Raising Events[^].

I want to warn you: don't even play with the idea of doing UI development at this moment, before you learn and very clearly understand all of the above. It would be programming by cookbook recipes, which would be very bad. You have to learn all that, and the best way would be doing it based on very simple console-only exercises at first.

—SA

Delegate and event on button click event in window form C#

3 solutions

Solution 2

Solution 3

Solution 1

Add your solution here

Preview 0