Introduction

Goal of the Tutorial

This tutorial aims to introduce you to lambda expressions and anonymous methods in C#. These are powerful features of the C# language that allow you to define methods in a concise manner, especially in places where delegates are required.

What You Will Learn

By the end of this tutorial, you will have a good understanding of:
- What lambda expressions and anonymous methods are
- The differences between lambda expressions and anonymous methods
- How and when to use lambda expressions and anonymous methods

Prerequisites

Before starting this tutorial, you should have a basic understanding of C# programming, including knowledge of delegates.

Step-by-Step Guide

Lambda Expressions

In C#, a lambda expression is an anonymous function that you can use to create delegates or expression tree types. It uses the => operator which reads as 'goes to'.

Here is the basic syntax of a lambda expression in C#:

(input-parameters) => { statement(s) };

Anonymous Methods

An anonymous method is like a regular method but it doesn't have a name and it can be defined using the delegate keyword. Here is the basic syntax:

delegate(parameters) { statement(s) };

Differences Between Lambda Expressions and Anonymous Methods

While lambda expressions and anonymous methods are similar, there are some important differences:

• Syntax: Lambda expressions use the => operator while anonymous methods use the delegate keyword.
• Implicitly Typed: Lambda expressions can be implicitly typed, meaning the compiler can infer the type of the input parameters. Anonymous methods cannot do this.
• this Scope: In a lambda expression, this refers to the class instance that contains the lambda expression. In an anonymous method, this refers to the delegate instance.

Code Examples

Example 1: Lambda Expression

Here is an example of a simple lambda expression that adds two numbers:

Func<int, int, int> add = (a, b) => a + b;
Console.WriteLine(add(5, 3)); // Outputs 8

In this example, Func<int, int, int> is a delegate that takes two integers as input and returns an integer. The lambda expression (a, b) => a + b takes two integers a and b, and returns their sum.

Example 2: Anonymous Method

Here is an equivalent anonymous method for the above lambda expression:

Func<int, int, int> add = delegate(int a, int b) { return a + b; };
Console.WriteLine(add(5, 3)); // Outputs 8

Summary

In this tutorial, we have covered lambda expressions and anonymous methods in C#, including their syntax, differences, and usage. The next step in your learning journey could be to explore other features of C#, such as LINQ, which makes heavy use of lambda expressions.

Practice Exercises

Exercise 1: Lambda Expression

Write a lambda expression that checks if a number is even or not.

Exercise 2: Anonymous Method

Write an anonymous method that checks if a string is a palindrome or not.

Solutions

Here are the solutions for the above exercises:

1. Lambda Expression:

Func<int, bool> isEven = n => n % 2 == 0;
Console.WriteLine(isEven(4)); // Outputs True

1. Anonymous Method:

Func<string, bool> isPalindrome = delegate(string s)
{
    string reversed = new string(s.Reverse().ToArray());
    return s == reversed;
};
Console.WriteLine(isPalindrome("radar")); // Outputs True

Continue practicing with more complex examples to strengthen your understanding of lambda expressions and anonymous methods.