IList<T> does not have "where"

Question

In a specific project at my work, I have a method that returns IList. But this interface does not contain where, or FindAll filters. However, when I open a new project, IList contains all. What is the difference?

Crews

Answer 1

Did you import System.Linq ?

Jolyn

@Crews - I agree with @Will Dean, it's important to accept answers that help you out from SO. It doesn't just give the answerer reputation, it lets future googlers know which answer helped you figure out your problem. – Chalaza

Answer 2

Nope. IEnumerable<T> has "where" as an extension method.

Assuming your project is .Net 3.5 or greater, you need to have using System.Linq;

Stoppage

IEnumerable<T> you mean. :) The plain old IEnumerable is not supported by LINQ - you have to do Cast/OfType first. – Rainarainah

@Noldorin: Yeah, I actually had <T>, but I forgot to put it in a code block and StackOverflow lost it... probably got rendered as a HTML tag. Thanks :) – Stoppage

Answer 3

You might find this useful: LINQ, Where() vs FindAll()

Nephritic

Answer 4

Check .NET Framework of opened framework, may be its .NET Fx 2.

System.Linq added in 3.5

Derbyshire

Answer 5

Here's a basic discussion of extension methods in general. As mentioned by others, the Where method is an extension method found in the System.Linq namespace so you need to import it in order to have intellisense detect the existence of those methods.

Debouch