No Overload for method 'Contains' takes 2 arguments with list and simple string

Question

Borrowing from the example here, I tried to do the following:

List<string> animals = new List<string> { "Horse", "Cat", "Dog" };
bool testCase = animals.Contains("horse", StringComparer.CurrentCultureIgnoreCase);

But just doing that, I get "No overload for method 'Contains' takes 2 arguments".

I also tried it as:

List<string> animals = new List<string> { "Horse", "Cat", "Dog" };
string testAnimal = "horse";
bool testCase = animals.Contains(testAnimal, StringComparer.CurrentCultureIgnoreCase);
testCase = animals.Contains((string)testAnimal, StringComparer.CurrentCultureIgnoreCase);

But both of those get the same error.

what am I missing here?

Loblolly

Does this answer your question? Searching a List<string> for an EXACT case insenitive match – Gilgamesh

No. The problem was that I didn't have system.linq, and that page doesn't mention it at all. – Loblolly

Answer 1

You are probably searching for the Linq-extension method Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>) which is documented here.

In your case, it is probably sufficient to just add using System.Linq; to the top of your source file and the method pops up.

Scutari

My system doesn't have the linq namespace... and I'm following the steps athttps://mcmap.net/q/512517/-the-type-or-namespace-name-39-linq-39-does-not-exist-in-the-namespace-39-system-39-duplicate and I don't even see system.core or system.data.linq – Loblolly

there we go... somehow my target framework was set to 2.0 ... yeesh... – Loblolly

Unless you are on a really old version of .net Framework (< 3.5(, you must have System.Linq available. – Arevalo

Answer 2

Note that the overloaded method is only available on target Win 10 version 1809 and higher.

Lowrey

Answer 3

you have to use the extension method Contains that is part of the namespace System.Linq. Just add this line on top of your file and the method with two arguments should be available.

using System.Linq; 

Backwoodsman