What is a lambda expression?

Utpal Vishwas 629 07 Jul 2023

Utpal Vishwas

Student

I am Utpal Vishwas from Uttar Pradesh. Have completed my B. Tech. course from MNNIT campus Prayagraj in 2022. I have good knowledge of computer networking.

1 Answers

Aryan Kumar 10 Jul 2023

A lambda expression in C# is an anonymous function that can be used to encapsulate a small amount of code. Lambda expressions are often used in functional programming, but they can also be used in other programming paradigms.

A lambda expression is defined using the lambda keyword. The syntax for a lambda expression is as follows:

Code snippet

(parameters) => expression

The parameters section is optional and can be used to specify the parameters that the lambda expression takes. The expression section is the body of the lambda expression and contains the code that the lambda expression executes.

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

Code snippet

(int x, int y) => x + y

This lambda expression takes two integers as parameters and returns the sum of the two integers.

Lambda expressions can be used in a variety of situations, such as:

Filtering collections: Lambda expressions can be used to filter collections of objects. For example, the following code uses a lambda expression to filter a list of numbers to only include the numbers that are greater than 10:

Code snippet

List<int> numbers = new List<int>();
numbers.Add(1);
numbers.Add(2);
numbers.Add(3);
numbers.Add(4);
numbers.Add(5);

List<int> filteredNumbers = numbers.Where((int number) => number > 10);

The Where() method takes a lambda expression as a parameter. The lambda expression in this case checks if the number is greater than 10. If the number is greater than 10, the number is added to the filteredNumbers list.

Mapping collections: Lambda expressions can also be used to map collections of objects. Mapping a collection means transforming each object in the collection into a new object. For example, the following code uses a lambda expression to map a list of numbers to a list of strings:

Code snippet

List<int> numbers = new List<int>();
numbers.Add(1);
numbers.Add(2);
numbers.Add(3);
numbers.Add(4);
numbers.Add(5);

List<string> strings = numbers.Select((int number) => number.ToString());

The Select() method takes a lambda expression as a parameter. The lambda expression in this case converts the number to a string. The strings are then added to the strings list.

Anonymous delegates: Lambda expressions can also be used to create anonymous delegates. Anonymous delegates are delegates that do not have a name. They can be used to encapsulate a small amount of code that can be executed later. For example, the following code uses a lambda expression to create an anonymous delegate that adds two numbers:

Code snippet

int addTwoNumbers(int x, int y) {
  return x + y;
}

// Create an anonymous delegate
var delegate = (int x, int y) => x + y;

// Call the anonymous delegate
int result = delegate(1, 2);

The addTwoNumbers() method takes two integers as parameters and returns the sum of the two integers. The delegate variable is an anonymous delegate that refers to the addTwoNumbers() method. The result variable is the result of calling the anonymous delegate with the values 1 and 2.

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What is a lambda expression?

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