Anonymous Method In C# (With Examples)

Last updated on July 18th, 2023 at 02:17 am

An anonymous method in C# is a method that doesn’t have a name. You can create an anonymous method using the delegate keyword and assign it to a variable of delegate type.

In this article, We will discuss about the Anonymous method with multiple examples.

What is Anonymous Method in C#?

An anonymous method in C# is a method without a name or return type. It consists only of the method body, which is a code block. It can be passed as a delegate parameter. The return type is automatically determined from the return statement within the method body.

Here are some simple points to understand:

• You can create an anonymous method using the delegate keyword with optional parameters. It can be assigned to a variable of the delegate type.
• Anonymous methods are inline statements or expressions that make the code easier to read and understand.
• They are useful when you want to directly associate an action with an event without creating a separate event handler function.
• Anonymous methods are useful for handling events.
• Variables or methods declared outside an anonymous method can be accessed inside it.
• Variables declared inside an anonymous method cannot be accessed outside of it.
• Anonymous methods can be passed as parameters to other methods or functions.

Syntax:

The following is the syntax to declare an anonymous method in C#.

delegate(Parameters)
{
    // Code Here.
};

Example: Anonymous Method

Here is an example of an anonymous method in C#.

using System;

class Program
{
    delegate void GreetingDelegate(string name);

    static void Main()
    {
        // Create an instance of the delegate and assign an anonymous method to it
        GreetingDelegate greeting = delegate (string name)
        {
            Console.WriteLine("Hello, " + name + "!");
        };

        // Call the delegate like a regular method
        greeting("Shekh Ali");

        Console.ReadLine();
    }
}

Code Explanation: 

In this example, we create an anonymous method using the delegate keyword. The anonymous method takes a string parameter called name and prints a greeting message to the console using the given name. 

We assign this anonymous method to a delegate named greeting.

When we call the delegate greeting("Shekh Ali"), it invokes the anonymous method, passing in the name “Shekh Ali”. 

As a result, the output will be:

Hello, Shekh Ali!

Example 2: Anonymous method in C#

Here is another example of an anonymous method in C#.

using System;
namespace AnonymousMethodDemo
{
    class Program
    {
        // Declaring a delegate
        public delegate int MyDelegate(int num1, int num2);

        static void Main(string[] args)
        {
            // Instantiating the delegate using an anonymous method

         MyDelegate myDelegate = delegate (int num1, int num2)
         {
            return num1 + num2;
         };
            Console.WriteLine(myDelegate(10,20));
        }
    }
    // Output: 30
}

Limitations of the Anonymous Method:

The following are the few limitations of the Anonymous method:

• Anonymous methods cannot be used to the left of the “is” operator.
• Jump statements such as goto, break, and continue are not allowed within an anonymous method.
• An anonymous method cannot access ref or out parameters from an outer scope.
• Anonymous methods cannot access unsafe code.
• Overloading an anonymous method is not possible.
• Anonymous methods cannot be used as the target of a virtual method call.
• Anonymous methods cannot be used as iterators or async methods.
• Anonymous methods cannot be used with the async/await keywords.

Example 3: Anonymous method as an event handler

We will use an anonymous method to define an event handler in the given example. This event handler will execute a specific action when the user clicks the submit button on the window form.

using System;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
           
    private void Form1_Load(object sender, EventArgs e)
        {
            // Creating Click Event handler using an Anonymous method
            btnSubmit.Click += delegate(object obj,EventArgs arg)
            {
                MessageBox.Show(" Hello !", "Anonymous method example");
            };
        }
    }
}

When the button is clicked, action will be performed directly in response to the Click event using an anonymous method, as shown in the image below.

As expected, a message box displays a “Hello” message when clicking the submit button.

Example 4: Anonymous method in a lambda expression

Here is an example of using an anonymous method in a lambda expression with code comments:

using System;

class Program
{
    delegate int CalculationDelegate(int a, int b);

    static void Main()
    {
        // Create an instance of the delegate and assign an anonymous method using a lambda expression
        CalculationDelegate calculation = (a, b) =>
        {
            return a + b;
        };

        // Call the delegate like a regular method
        int result = calculation(5, 3);
        Console.WriteLine("The result is: " + result);

        Console.ReadLine();
    }
}

Code Explanation:

In this example, we use an anonymous method in a lambda expression to create an instance of a delegate named calculation. The anonymous method takes two integer parameters, a and b, and returns their sum.

When we call the delegate calculation(5, 3), it invokes the anonymous method with the values 5 and 3, which results in their sum. 

The output will be:

The result is: 8

Example 5: Anonymous method as a parameter

Here is an example of using an anonymous method as a parameter in C#:

using System;

class Program
{
    // Delegate definition
    delegate void ProcessDelegate(string message);

    // Method that takes a delegate as a parameter
    static void PerformAction(string message, ProcessDelegate action)
    {
        // Execute the delegate passed as a parameter
        action(message);
    }

    static void Main()
    {
        // Call PerformAction method and pass an anonymous method as a parameter
        PerformAction("Hello World!", delegate(string message)
        {
            Console.WriteLine("Message received: " + message);
        });

        Console.ReadLine();
    }
}

Output:

Message received: Hello World!

References: MSDN – Lambda expressions

FAQs:

Here are some frequently asked questions (FAQs) about anonymous methods in C#:

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Shekh Ali

Meet Shekh Ali, a skilled Software engineer and passionate blogger with an MCA degree and 8+ years of experience in the field. He enjoys sharing his expertise in C#, Java, SQL, Design Patterns, and other related topics through his writing. When he's not coding, Shekh Ali can often indulge in his passions for reading books and fitness training.

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