What is this .. =

Question

Can you tell me what this ( => ) means in the following context? IEnumerable query = names .Where(s => s.Length == 5) .OrderBy(s => s) .Select(s => s.ToUpper());

Alan · Answer

Hi Michael Yes I am reasonably well versed in LINQ but that's only because I've been following it for the last couple of years whilst it's been in development so I was able to hit the ground running when VS 2008 came out. There's plenty of resources on LINQ over at the .NET Framework developer center: http://msdn2.microsoft.com/en-gb/netframework/aa904594.aspx One thing you do need to get used to now is the functional style of programming which lambda expressions entail but is rather foreign to most C# developers including myself. Matthew Cochran has written a number of excellent articles about functional programming using C# on this site: http://www.c-sharpcorner.com/Authors/AuthorDetails.aspx?AuthorID=rmcochran I do know what you mean about it being difficult to keep up with MS throwing new stuff at us every other week - or so it seems :)

Michal Moore · Answer

Alan are you well versed in LINQ and all this already? I find it nearly impossible to keep up.

Michal Moore · Answer

thanks Alan... I could not find anything in google that referred to => but after reading your response I used lambda expression operator and found this http://msdn2.microsoft.com/en-us/library/bb397687.aspx thanks very much!

Alan · Answer

=> is the operator used for creating lambda expressions in C# 3.0. A lambda expression is similar to (but more powerful than) an anonymous method which was introduced in C# 2.0. In other words it's a function which is written 'inline' and can be assigned to a compatible delegate. What's at the LHS of the => is the parameter (or parameters) of the function and what's at the RHS is the return value of the function. It's also possible to have a block of statements rather than just an expression on the RHS. Unless you're already familiar with other features of C# 3.0 such as extension methods and type inference it's difficult to explain how that code works but what it does is to examine each string s in the string collection names and return a query consisting of all such strings whose length is 5 converted to upper case and in alpahabetical order.

What is this .. =>