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Understand Lambda Expressions in 3 minutes

, 5 Mar 2013 CPOL
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Lambda expressions short tutorial.
  1. What is a Lambda Expression?
  2. A lambda expression is an anonymous function and it is mostly used to create delegates in LINQ. Simply put, it's a method without a declaration, i.e., access modifier, return value declaration, and name. 

  3. Why do we need lambda expressions? (Why would we need to write a method without a name?)
  4. Convenience. It's a shorthand that allows you to write a method in the same place you are going to use it. Especially useful in places where a method is being used only once, and the method definition is short. It saves you the effort of declaring and writing a separate method to the containing class.


    1. Reduced typing. No need to specify the name of the function, its return type, and its access modifier. 
    2. When reading the code you don't need to look elsewhere for the method's definition. 

    Lambda expressions should be short. A complex definition makes the calling code difficult to read. 

  5. How do we define a lambda expression? 
  6. Lambda basic definition: Parameters => Executed code.

Simple example

n => n % 2 == 1 
  • n is the input parameter
  • n % 2 == 1 is the expression

You can read n => n % 2 == 1 like: "input parameter named n goes to anonymous function which returns true if the input is odd".

Same example (now execute the lambda):

List<int> numbers = new List<int>{11,37,52};
List<int> oddNumbers = numbers.where(n => n % 2 == 1).ToList();
//Now oddNumbers is equal to 11 and 37

That's all, now you know the basics of Lambda Expressions.

  • * I didn't mention expression trees/run time advantages of lambda expression due to limited scope.
  • * Reference Lambda Expression tutorial


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Dan Avidar

United States United States
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Comments and Discussions

GeneralWell Explained PinmemberPratimaG11-Mar-13 6:11 
GeneralMy vote of 4 PinmemberiAmit196-Mar-13 18:36 
QuestionVery well explained PinmemberMember 93414686-Mar-13 7:48 
AnswerRe: Very well explained PinmemberDan Avidar6-Mar-13 8:20 
GeneralMy vote of 5 PinmemberOmid Babaei6-Mar-13 1:33 
GeneralMy vote of 5 Pinmembersconnor28-Jan-13 17:36 
GeneralMy vote of 5 Pinmemberpatil9928-Jan-13 0:15 
GeneralMy vote of 1 PinmemberNemo19665-Dec-12 13:16 
Poor explanation
GeneralRe: My vote of 1 Pinmembercigwork5-Dec-12 22:15 
GeneralRe: My vote of 1 PinmemberRoger Tranchez16-Dec-12 0:35 
QuestionWhat about the link to PinmemberKlaus Luedenscheidt4-Dec-12 20:34 
QuestionCongratulations PinmemberGlen Harvy4-Dec-12 18:51 
GeneralMy vote of 5 PinmemberNosugar4-Oct-12 0:39 
QuestionMy Vote of 5! Pinmemberakosidab19-Jul-12 0:01 
QuestionUnderstand Lambda Expression in 3 min - Wonderfull PinmemberSen K Mathew16-Jul-12 2:11 
GeneralReason for my vote of 5 Great and To the point PinmemberTanzeelurRehman13-Jan-12 1:26 
GeneralReason for my vote of 5 Short and to the point. Very clear a... PinmemberPantelis Chatzinikolis1-Jan-12 16:16 
GeneralReason for my vote of 5 Nice article. Clarifies on the very ... PinmemberAnandachetan Elikapati29-Dec-11 16:44 
GeneralWhat is a declartion? Pinmemberjenkstom20-Dec-11 4:38 
GeneralReason for my vote of 5 Great, easy to understand. Pinmemberchuckamus_prime20-Dec-11 4:04 
GeneralReason for my vote of 3 its easy to understand, but more exa... PinmemberMohammad_Denmark19-Dec-11 23:45 
GeneralReason for my vote of 5 It's easy to understand. :) PinmemberBaoyu Mou19-Dec-11 17:57 
General:) Think I have spent too long trying to fight the PC establ... PinmemberBob100019-Dec-11 15:12 
GeneralReason for my vote of 1 ou used the most irritating of phase... PinmemberBob100019-Dec-11 12:55 
GeneralRe: Ok, I will give it my attention next time :) PinmemberRonaldo jer19-Dec-11 14:06 

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