IList <T> does not have a "where"

Question

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

Answer 1

Have you imported System.Linq?

Answer 2

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

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

Answer 3

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

Answer 4

Check out the .NET Framework open environment, maybe its .NET Fx 2.

System.Linq added in 3.5

Answer 5

Here is the main discussion of extension methods in general. As others have mentioned, the Where method is an extension method found in the System.Linq namespace, so you need to import it so that intellisense detects the existence of these methods.