Namespace constant in C#

Question

Is there any way to define a constant for an entire namespace, rather than just within a class? For example:

namespace MyNamespace
{    
    public const string MY_CONST = "Test";

    static class Program
    {
    }
}

Gives a compile error as follows:

Expected class, delegate, enum, interface, or struct

Note that "constant variable" is an oxymoron. Variables vary, that's why they're called "variables". Constants remain constant, that's why they're called constants. Variables are storage *locations*, constants are *values*. They are completely different; there can be no such thing as a "constant variable". — Eric Lippert, May 12 '10 at 14:14

score 117 · Accepted Answer · edited Nov 17 '20 at 15:34

117

I believe it's not possible. But you can create a Class with only constants.

public static class GlobalVar
{
    public const string MY_CONST = "Test";
}

and then use it like

class Program
{
    static void Main()
    {
        Console.WriteLine(GlobalVar.MY_CONST);
    }
}

edited Nov 17 '20 at 15:34

alinsoar

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answered May 12 '10 at 11:35

RvdK

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19

+1 as this is the Microsoft recommended method http://msdn.microsoft.com/en-us/library/bb397677.aspx – Bryan May 12 '10 at 11:41
1

As an aside, another way to implement this is with your web.config or app.config (depending on which one you have). https://stackoverflow.com/a/4256864/105539 – Volomike Oct 17 '17 at 00:05

score 14 · Answer 2 · edited Apr 22 '15 at 07:17

14

This is not possible

From MSDN:

The const keyword is used to modify a declaration of a field or local variable.

Since you can only have a field or local variable within a class, this means you cannot have a global const. (i.e namespace const)

edited Apr 22 '15 at 07:17

KenIchi

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answered May 12 '10 at 11:32

Oded

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score 6 · Answer 3 · edited Aug 12 '21 at 13:40

6

You can use the constants in your other classes if you add the "Using Static" too:

using static MyNameSpace.MyGlobals;

namespace MyNameSpace {
    public static class MyGlobals{
        public const bool SAVE_LOGSPACE = true;
        public static readonly DateTime BACKTEST_START_DATE = new DateTime(2019,03,01);
    }
}

edited Aug 12 '21 at 13:40

geisterfurz007

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answered Mar 30 '19 at 00:09

MrCalico

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thanks, also works with `using static MyNameSpace.MyEnum;` – Gregor y Jan 26 '23 at 19:28

score 3 · Answer 4 · answered May 12 '10 at 11:34

3

No, there is not. Put it in a static class or enum.

answered May 12 '10 at 11:34

Svante Svenson

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score 0 · Answer 5 · answered May 09 '22 at 11:21

I would define a public static class with constants:

namespace Constants
{
    public static class Const
    {
        public const int ConstInt = 420;
    }
}

Inside my Program.cs, i would add the following using:

using static Constants.Const;
using static System.Console;

Now you can freely use the defined constants (which are static by default) and static Console-Methods, e. g.

class Program
{
    static void Main(string[] args)
    {
        WriteLine(ConstInt);
    }
}

Namespace constant in C#

5 Answers5

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