Can a static class be imported in C# as in VB.NET?

Question

Is there a way to "Import" a static class in C# such as System.Math?

I have included a comparison.

Imports System.Math

Module Module1

    Sub Main()
        Dim x As Double = Cos(3.14) ''This works
    End Sub

End Module

Vs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Math; //Cannot import a class like a namespace

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            double x = Math.Cos(3.14);
            double y = Cos(3.14); //Cos does not exist in current context
        }
    }
}

There isn't a way to do that in C#. I also [would like to have something like it](http://codecrafter.blogspot.com/2009/09/c-static-classes-are-not-real-classes.html). — Jordão, Oct 09 '10 at 02:17
As of C# 6, [the answer is now YES](https://stackoverflow.com/a/34777014/199364). — ToolmakerSteve, Dec 23 '17 at 14:22

score 10 · Accepted Answer · edited Dec 23 '17 at 14:24

UPDATE: As of C# 6, the answer is now YES.

No, in C# you can only import namespaces, not classes.

However, you can give it a shorter alias:

using M = System.Math;

Now you can use the alias instead of the class name:

double y = M.Cos(3.14);

Be careful how you use it, though. Most of the time the code is more readable with a descriptive name like Math rather than a cryptic M.

Another use for this is to import a single class from a namespace, for example to avoid conflicts between class names:

using StringBuilder = System.Text.StringBuilder;

Now only the StringBuilder class from the System.Text namespace is directly available.

score 9 · Answer 2 · edited Aug 16 '18 at 20:43

An updated answer to this question is YES as of C# 6.0, which provides a using static feature. So, for instance, using static System.Math; allows the static members of System.Math to be accessed without future qualification of the Math class.

Related SO answers:
Can Math references be shortened in C#?
How do I use the C#6 “Using static” feature?

External References:
GitHub - New Language Features in C# 6
Intellitect - Static Using Statement in C# 6.0

score 5 · Answer 3 · answered Oct 09 '10 at 01:12

5

There isn't. You need to explicitly invoke methods as features of classes in C#.

answered Oct 09 '10 at 01:12

CesarGon

15,099
6
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score 2 · Answer 4 · edited Oct 09 '10 at 01:21

I was thinking maybe some form of extension methods? This could be tweaked of course.

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            double x = Math.Cos(3.14);
            double y = 3.14;
            Console.WriteLine(y.Cos());
        }
    }

    public static class Extension
    {
        public static double Cos(this double d)
        {
            return Math.Cos(d);
        }
    }
}

score 0 · Answer 5 · edited Dec 23 '17 at 14:26

0

Starting with C# version 6, static classes can be imported by the following syntax.

using static System.Console;

edited Dec 23 '17 at 14:26

ToolmakerSteve

18,547
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answered Jan 26 '16 at 09:52

Nantharupan

594
3
15

Can a static class be imported in C# as in VB.NET?

5 Answers5