C# Array.Contains () compilation error

Question

I'm trying to use the Array.Contains () method in C#, and for some reason it's failing to compile, eve though I believe that I'm using C# 4.0, and C# should support this in 3.0 and later.

if (! args.Contains ("-m"))     Console.WriteLine ("You must provide a message for this commit."); 

And I get this error:

Main.cs(42,15): error CS1061: 'System.Array' does not contain a definition for 'Contains' and no extension method 'Contains' accepting a first argument of type 'System.Array' could be found (are you missing a using directive or an assembly reference?)

I am compiling from the command line, with no options: "csc Main.exe".

Answer 1

You need to add using System.Linq; at the beginning of your program.

Answer 2

Did you forget using System.Linq?

By the way, if you can't use LINQ there are many other options such as Array.Exists.