CODEWITHSUNDEEP
.netstaticlanguage-designconstants
dance2die
dance2die

Reputation: 36985

Why is a const variable available within a static method?

I have been writing code without realizing WHY I can access constant values within static methods.

Why is it possible to access const values without declaring it as static?

E.g.) It's legal to call IMAGE_FILE_EXTENSION within AddImageToDocument(...) 

public abstract class ImageDocumentReplacer : DocumentReplacer
{
    private const string IMAGE_FILE_EXTENSION = ".tif";

    private static void AddImageToDocument(int documentId, string separatedPath)
    {
        Console.WriteLine(IMAGE_FILE_EXTENSION);
    }
}

Upvotes: 7

Views: 2210

Answers (3)

Mehrdad Afshari
Mehrdad Afshari

Reputation: 422320

const members are implicitly static. They belong to the class rather than a specific instance. As a consequence, you can't use this.myConstant but MyClass.myConstant.

Quoting the C# 3.0 specification (section §10.4 Constants):

Even though constants are considered static members, a constant-declaration neither requires nor allows a static modifier. It is an error for the same modifier to appear multiple times in a constant declaration.

Upvotes: 19

Michael Borgwardt
Michael Borgwardt

Reputation: 346566

Why should it not be possible? Since the value is fixed at compile time, there is no possible inconsistency (as there would be with variables or readonly fields that can be initialized to different values for different instances at runtime)

Upvotes: 2

n8wrl
n8wrl

Reputation: 19765

I would expect that, since a constant can't change instance-to-instance, that makes them safe to access from a static method.

Upvotes: 1

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