.NET List.Distinct

Question

I'm using .NET 3.5. Why am I still be getting:

does not contain a definition for 'Distinct'

with this code:

using System.Collections.Generic;

       //.. . . . . code


    List<string> Words = new List<string>();
       // many strings added here . . .
    Words = Words.Distinct().ToList();

Answer 1

Are you

using System.Linq;

?

Distinct is an extension method defined in System.Linq.Enumerable so you need to add that using statement.

And don't forget to add a reference to System.Core.dll (if you're using VS2008, this has already been done for you).

Answer 2

You forgot to add

using System.Linq;

Distinct is an extension method that is defined in System.Linq.Enumerable, so you can only call it if you import that namespace.

You'll also need to add a reference to System.Core.dll.
If you created the project as a .Net 3.5 project, it will already be referenced; if you upgraded it from .Net 2 or 3, you'll have to add the reference yourself.