What does the C# operator => mean?

Question

Answers to a recent post (Any chances to imitate times() Ruby method in C#?) use the => operator in the usage examples. What does this operator do? I can't locate it in my C# book, and it is hard to search for symbols like this online. (I couldn't find it.)

Answer 1

It's not really an operator as such, it's part of the syntax for lambda expressions. In particular => is the bit which separates the parameters from the body of the lambda expression.

Does your book cover C# 3.0? If not, it won't include lambda expressions. If it does, it should really cover them! Hopefully with the right terminology, you'll be able to find it in the TOC or index.

EDIT: A bit more information: A lambda expression is a piece of syntactic sugar to either create an instance of a delegate or an expression tree (the latter being new to .NET 3.5). Lambda expressions almost entirely replace anonymous methods (from C# 2.0) although they don't support the notion of "I don't care about the parameters" in the way that anonymous methods do.

Answer 2

That will be for a lambda expression:

http://msdn.microsoft.com/en-us/library/bb397687.aspx

An example is here:

MyControl.OnMouseDown += (sender, e) =>
{
  // Do something in the mouse down event
};

Here I have created a lambda expression event delegate. It basically saves me from having to create a separate function for it in the class.

Answer 3

A lambda expression is an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types.

All lambda expressions use the lambda operator =>, which is read as "goes to". The left side of the lambda operator specifies the input parameters (if any) and the right side holds the expression or statement block

http://msdn.microsoft.com/en-us/library/bb397687.aspx

Answer 4

The => token is called the lambda operator.

It is used in lambda expressions to separate the input variables on the left side from the lambda body on the right side.

MSDN