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Understand Lambda Expressions in 3 minutes

, 5 Mar 2013 CPOL 278.1K 112
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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.

    Benefits: 

    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

License

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

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About the Author

Dan Avidar
United States United States
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QuestionSuper simple explanation Pin
Member 109346763-Aug-15 22:02
memberMember 109346763-Aug-15 22:02 
GeneralMy vote of 5 Pin
Member 110351022-Aug-15 9:55
memberMember 110351022-Aug-15 9:55 
GeneralMy vote of 5 Pin
Bunny Charles27-Apr-15 21:10
memberBunny Charles27-Apr-15 21:10 
Questionlink to "more info" is a virus Pin
Member 105394751-Feb-15 13:36
memberMember 105394751-Feb-15 13:36 
GeneralMy vote of 4 Pin
akshay08-Jan-15 1:14
memberakshay08-Jan-15 1:14 
GeneralMy vote of 5 Pin
YannisPs5-Nov-14 0:59
memberYannisPs5-Nov-14 0:59 
QuestionThank you soooo much Pin
Don Driskell21-Oct-14 7:53
memberDon Driskell21-Oct-14 7:53 
GeneralPerfect Article Pin
Bala_Subramani26-Jun-14 1:48
memberBala_Subramani26-Jun-14 1:48 
GeneralMy vote of 5 Pin
sandeepmgupta10-Jun-14 22:13
membersandeepmgupta10-Jun-14 22:13 
GeneralMy vote of 5 Pin
Dhanu7865-Jun-14 19:36
memberDhanu7865-Jun-14 19:36 
QuestionThanks Pin
afablulo4-Jun-14 14:06
memberafablulo4-Jun-14 14:06 
GeneralMy vote of 5 Pin
Paw Møller3-Jun-14 14:07
memberPaw Møller3-Jun-14 14:07 
QuestionNicely written Pin
StarsAreUs2-Jun-14 13:28
memberStarsAreUs2-Jun-14 13:28 
AnswerRe: Nicely written Pin
Divyam Sharma22-May-15 19:38
professionalDivyam Sharma22-May-15 19:38 
QuestionThanks Pin
Andrew Torrance1-Apr-14 23:48
memberAndrew Torrance1-Apr-14 23:48 
QuestionThanks! Pin
proloser24-Feb-14 14:30
memberproloser24-Feb-14 14:30 
QuestionNice but the last link is obsolete Pin
rj475625-Jan-14 18:13
memberrj475625-Jan-14 18:13 
AnswerRe: Nice but the last link is obsolete Pin
Nick Alexeev16-Apr-14 9:25
memberNick Alexeev16-Apr-14 9:25 
GeneralRe: Nice but the last link is obsolete Pin
rj475621-Apr-14 18:14
memberrj475621-Apr-14 18:14 
QuestionMy vote of 5 Pin
Member 323305517-Dec-13 19:53
memberMember 323305517-Dec-13 19:53 
GeneralThe simplest article of confused topic so far. Thank You Pin
Deepak K Gupta29-Sep-13 10:06
memberDeepak K Gupta29-Sep-13 10:06 
GeneralMy vote of 5 Pin
Tarun Y Mangukiya2-Sep-13 4:57
memberTarun Y Mangukiya2-Sep-13 4:57 
GeneralMy vote of 5 Pin
Edgar ramirez24-Aug-13 7:54
professionalEdgar ramirez24-Aug-13 7:54 
QuestionSorry... Pin
jhewitt999923-Aug-13 11:45
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AnswerRe: Sorry... Pin
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