What namespace will a class have if no namespace is defined

Question

In C#, if I create a class with no namespace, what namespace will I use when trying to instantiate the class?

For example, assume main is...

namespace NamespaceTests { class Program { static void Main(string[] args) { } } }

... and assume my namespace-less class is ...

public class test { public string SayHello() { return "Hello World!"; } }

... and assume I have another class by the same name, but having the default namespace...

namespace NamespaceTests { public class test { public string SayHello() { return "Hello Moon..."; } } }

... how would I modify main to include an instance of the namespace-less class and call 'SayHello' to retrieve the message "Hello World!"? Specifically, how would I fully qualify the namespace-less instance of class 'test', especially considering I may have another class also called 'test' but having a namespace, so I need to distinguish...

possible duplicate of explicitly refer to a class without a namespace in C# — chue x
– chue x, Commented Aug 26, 2014 at 2:30

Jason Down · Accepted Answer · 2014-08-27 18:12:09Z

85

It's in the global namespace and can be referenced like this:

var x = new global::test();

edited Aug 27, 2014 at 18:12

Jason Down

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answered Aug 25, 2014 at 17:49

David Crowell

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2 Comments

barrypicker Over a year ago

Thanks David - example worked perfect. Your answer was 10 seconds before @itsme86 - award to you sir. +1 for example...

GarDavis Over a year ago

This solved an ambiguous reference due to a class named the same. One had a namespace and one didn't. It was attempting to call the one with the namespace and getting an exception: error CS0117: 'System.Web.Mvc.HtmlHelperExtensions' does not contain a definition for 'RenderPartialViewToString

Community · Accepted Answer · 2020-06-20 09:12:55Z

Types not defined within a namespace will be in the global namespace.

The global contextual keyword, when it comes before the :: operator, refers to the global namespace, which is the default namespace for any C# program and is otherwise unnamed.

The following example shows how to use the global contextual keyword to specify that the class TestApp is defined in the global namespace:

C# class TestClass : global::TestApp { }

andreyk2 Hohlov · Accepted Answer · 2020-01-27 18:10:14Z

In the addition to above answers, it is important to note, what all Type, regardless of its declaration location, has a "fully qualified name", which begins from "global::"

From "O'Relly. C# in a Nutshell":

All type names are converted to fully qualified names at compile time. Intermediate Language (IL) code contains no unqualified or partially qualified names

It's true that you can program in C# using fully qualified objects and avoiding using statements. The using statements are purely syntactical sugar which compresses the code to make it easier to read. When there is a large degree of confusion around classes with similar names it may make sense to fully qualify types and not have using statements for extra clarity.

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