C# Academy · Lesson

Exploring Delegates and Lambdas

Understand delegates and lambda expressions for concise and flexible code.

Lesson 4 of 510 steps

Exploring Delegates and Lambdas is a free C# Academy lesson on CoddyKit. This is lesson 4 of 5. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the C# Academy learning path, and your progress syncs across the web and the CoddyKit app. The C# Academy course includes 5 lessons in total.

Using Lambdas with Delegates

Lambdas can be assigned to delegates directly. Example:

Exploring Delegates and Lambdas — illustration 1

What is a Delegate?

A delegate is a type that holds references to methods with a specific signature. Delegates allow methods to be passed as parameters or assigned dynamically.

Example: Delegates are often used for callbacks and event handling.

Defining and Using Delegates

You can define a delegate using the delegate keyword. Example:

Key Point: Delegates provide a way to encapsulate methods.

using System;

class Program {
    // Define a delegate
    public delegate void PrintDelegate(string message);

    static void Main() {
        PrintDelegate print = PrintMessage; // Assign method to delegate
        print("Hello, Delegates!"); // Call the method via the delegate
    }

    static void PrintMessage(string message) {
        Console.WriteLine(message);
    }
}

What is a Lambda Expression?

A lambda expression is a concise way to represent an anonymous method in C#. It uses the syntax (parameters) => expression.

Example: (x, y) => x + y represents a method that adds two numbers.

Tip: Lambdas are often used with LINQ and delegates for brevity and clarity.

Lambda Expressions with Delegates

Using Lambdas with Delegates

Lambdas can be assigned to delegates directly. Example:

Key Point: Lambdas make your code more concise and readable.

using System;

class Program {
    public delegate int MathOperation(int x, int y);

    static void Main() {
        MathOperation add = (x, y) => x + y; // Lambda for addition
        Console.WriteLine("Result: " + add(10, 20)); // Outputs: Result: 30
    }
}

Multicast Delegates

A single delegate can reference multiple methods. All methods are invoked in order. Example:

using System;

class Program {
    public delegate void Notify(string message);

    static void Main() {
        Notify notify = PrintMessage;
        notify += LogMessage;

        notify("Hello, Multicast Delegates!"); // Calls both methods
    }

    static void PrintMessage(string message) {
        Console.WriteLine("Print: " + message);
    }

    static void LogMessage(string message) {
        Console.WriteLine("Log: " + message);
    }
}

Practice Challenge

Create a program that uses a delegate StringOperation to perform string manipulations like converting to uppercase and reversing a string. Example:

using System;

class Program {
    public delegate string StringOperation(string input);

    static void Main() {
        StringOperation operations = ToUpperCase;
        operations += ReverseString;

        string input = "Hello";
        foreach (var operation in operations.GetInvocationList()) {
            Console.WriteLine(((StringOperation)operation)(input));
        }
    }

    static string ToUpperCase(string input) {
        return input.ToUpper();
    }

    static string ReverseString(string input) {
        char[] chars = input.ToCharArray();
        Array.Reverse(chars);
        return new string(chars);
    }
}

Best Practices for Delegates and Lambdas

Here are some best practices:

Use delegates to implement callbacks and event handling.
Prefer lambda expressions for concise and clear code.
Combine lambdas with LINQ for efficient data processing.
Avoid overly complex lambdas to maintain readability.

Tip: Use meaningful parameter names in lambdas to improve code clarity.

Great Job!

Congratulations! You’ve learned how to use delegates and lambda expressions to write functional and event-driven code in C#. In the next lesson, we’ll explore reflection in C#, a powerful feature for runtime type analysis. Let’s keep coding!

Exploring Delegates and Lambdas — illustration 10

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Frequently Asked Questions

Is the “Exploring Delegates and Lambdas” lesson free?

Yes — the full text of “Exploring Delegates and Lambdas” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the C# Academy course, upgrade to CoddyKit PRO. The C# Academy course includes 5 lessons in total.

What will I learn in “Exploring Delegates and Lambdas”?

Understand delegates and lambda expressions for concise and flexible code. You practise C# Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start C# Academy?

No prior experience is required. C# Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 4 of 5.

How long does the “Exploring Delegates and Lambdas” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this C# Academy lesson?

Yes. Every C# Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

Generics in C#
Async and Await: Working with Asynchronous Code
Understanding Threading and Tasks
Exploring Delegates and Lambdas
Understanding Reflection in C#

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