using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    private static Form f1 = new Form();

    public static void Main()

    {

        f1.button1.Text = "Button 1";

        f1.button2.Text = "Button 2";

        // The Click method will change the buttons but the change 

        // will only be within the Click method. Not outside.

        f1.button1.Click(f1.button1, EventArgs.Empty);

        // This will still write "Button 1"

        Console.WriteLine(f1.button1.Text);

        // Now if we do the assignment like this

        f1.button1 = f1.button2;

        f1.button1.Click(f1.button1, EventArgs.Empty);

        // this will write "Button 2"

        Console.WriteLine(f1.button1.Text);

        // Now pass as reference

        // We will pass button3 whose text is "Button 3" but it will be assigned

        // to button4, so the output will be "Button 4"

        f1.button3.Text = "Button 3";

        f1.button4.Text = "Button 4";

        button1_Click(ref f1.button3, EventArgs.Empty);

        Console.WriteLine(f1.button3.Text);

    }

​

    public static void button1_Click(ref Button sender, EventArgs e)

    {

        sender = f1.button4;

    }

}

​

public class Form

{

    public Button button1 = new Button();

    public Button button2 = new Button();

    public Button button3 = new Button();

    public Button button4 = new Button();

    public Form()

    {

        button1.Click += button1_Click;

        button2.Click += button1_Click;

    }

​

    public void button1_Click(object sender, EventArgs e)

    {

        var clickedButton = (Button)sender;

        clickedButton = this.button2;

    }

}

​

public class Button

{

    public EventHandler Click;

    public string Text

    {

        get;

        set;

    }

}