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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?

Rup
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bileyazan
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5 Answers5

39

Did you import System.Linq ?

ScottE
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  • @bileyazan - 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. – Dave McClelland Jul 21 '10 at 13:06
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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;

Brian Genisio
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  • `IEnumerable` you mean. :) The plain old `IEnumerable` is not supported by LINQ - you have to do `Cast`/`OfType` first. – Noldorin Jul 21 '10 at 12:58
  • @Noldorin: Yeah, I actually had ``, but I forgot to put it in a code block and StackOverflow lost it... probably got rendered as a HTML tag. Thanks :) – Brian Genisio Jul 21 '10 at 13:03
2

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

Community
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Will Dean
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1

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

System.Linq added in 3.5

Sandeep Kumar M
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1

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.

Steve Mitcham
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