What does this way of writing mean?

Question

This is probably a stupid question, but when I see code like this

var newList = list.OrderBy(x => x.Product.Name).toList();

I wonder that does the (x => x.Product.Name) mean?
Like, what is x and what does the => mean?

I don't know what to search for in order to obtain more information on this subject, any help would be appreciated, thank you.

(input parameters) => expression read this https://msdn.microsoft.com/en-us/library/bb397687.aspx — Harry, Apr 28 '15 at 14:15
@Mike if you know that they're called that. You can also search for "C# equals greater than". — CodeCaster, Apr 28 '15 at 14:17
Just to add, for searching programming terms like that, use http://symbolhound.com/ , I searched for `C# =>` and look at the [results](http://symbolhound.com/?q=C%23+%3D%3E) — Habib, Apr 28 '15 at 14:36

score 0 · Answer 1 · answered Apr 28 '15 at 14:15

0

Look on google for Lambda Expression. Here is a link to the MS page for Lambda Expressions - https://msdn.microsoft.com/en-us/library/bb397687.aspx

answered Apr 28 '15 at 14:15

czuroski

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score 0 · Answer 2 · answered Apr 28 '15 at 14:15

It's called a Lambda Expression.

A lambda expression is a way of passing a method as a parameter. The lambda expression above could be written as a method, possibly like this:

public string GetProductName(Thing x)
{
     return x.Product.Name;
}

So we see that x is a parameter into the method, or lambda expression in this case.

The OrderBy method in LINQ then uses this "method", or lambda expression, to know how to sort the list - OrderBy itself knows nothing about your objects or how to sort them, so we pass in a lambda which order by invokes.

In the case of IQueryable, lambda expressions are not actually code that gets invoked, but rather an expression tree is built. A lambda can be used to satisfy a delegate, or it can be used to build an expression tree. This is a bit of a complex subject, but worth mentioning.

What does this way of writing mean?

2 Answers2