Anonymous Method in C#

Vineet Kumar Saini
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Article

Introduction

Anonymous Methods are a new feature of C# v2.0. Anonymous Methods are similar to delegates in C#, but require less code. A method without a name is called an anonymous method. An anonymous method is different from regular methods. This method is not declared as a simple method or regular method.

Benefits of anonymous methods
Implement an anonymous method
Implement anonymous methods that use delegate parameters

Benefits of Anonymous Methods

Anonymous methods are used to define delegates and to write inline functions. The benefit of anonymous methods is, improve development experience over using delegates. The main benefits of anonymous methods is to implement delegates with less code.

Implementing an Anonymous Method

An anonymous method uses the keyword, delegate, instead of a method name. This is followed by the body of the method. Typical usage of an anonymous method is to assign it to an event.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace Anonymous_Method
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            Button btnHello = new Button();
            btnHello.Text = "Hello";
            btnHello.Click +=
                delegate
                {
                    MessageBox.Show("Hello Vineet...");
                };
            Controls.Add(btnHello);
        }
        private void Form1_Load(object sender, EventArgs e)
        {
        }
    }
}

Code Description

The code shown above instantiates a Button control and sets its text to "Hello". This code uses an anonymous method inside of a method, but the body of the anonymous method doesn't execute with the rest of the code. When you run the program and click the Hello button, you will see a message box i.e. "Hello Vineet.." . The Controls.Add, adds the new button control to the window. You can say that the preceding program uses an anonymous method because it uses the delegate keyword.

Output

Implement anonymous methods that use delegate parameters

In the example above we did not use parameters in the delegate but you can use of parameters in a delegate.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace Anonymous_Method
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            Button btnHello = new Button();
            btnHello.Text = "Hello";
            btnHello.Click +=
                delegate
                {
                    MessageBox.Show("Hello Vineet...");
                };
            Button btnGoodBye = new Button();
            btnGoodBye.Text = "Goodbye...";
            btnGoodBye.Left = btnHello.Width + 5;
            btnGoodBye.Click +=
                delegate(object sender, EventArgs e)
                {
                    string message = (sender as Button).Text;
                    MessageBox.Show(message);
                };
            Controls.Add(btnHello);
            Controls.Add(btnGoodBye);
        }
        private void Form1_Load(object sender, EventArgs e)
        {
        }
    }
}

Code Description

In the preceding example the delegate keyword has a parameter; this parameter must match the delegate type of the event that the anonymous method is being hooked up to. When you run the program and click the Goodbye button, you will see a message box i.e. "Goodbye.." .

Output