Missing Dictionary<TKey,TValue>.KeyCollection Extension Methods .NET 3.5 (C#)

Question

Perhaps I'm missing something with the concept of Extension Methods, but I cannot gain access to the Extension Methods within the KeyCollection Class as defined here: http://msdn.microsoft.com/en-us/library/dk7e2d8e.aspx .

Using the following code excerpt:

   Dictionary<int, int> foo = new Dictionary<int,int>();
   foo.Add(1,1);
   Dictionary<int, int>.KeyCollection kc = foo.Keys;

I can only gain access to the "standard" KeyCollection methods (CopyTo, Equals, Finalize, etc) but cannot gain access to the extension methods (Aggregate, All, Any, etc).

Any help would be greatly appreciated! Thank you!

Answer 1

I just tried it and it looks like I can.

You didn't forget

using System.Linq;

did you?

Answer 2

您是否错过了在课程顶部using System.Linq语句？