Namespaces

Namespaces declare scopes:

namespace SomeNamespace 
{
	class SomeClass { }
}

Namespace declarations can also be file-scoped:

using SomeNamespace; // Imports all classes from namespace.

Imports (`using` Directive)

using SomeNamespace;

using SomeAlias = Really.Long.Nested.Namespace;

The global modifier has the same effect as adding the same using directive to every source file in a project:

global using SomeNamespace;

Can also be added to project file instead:

<Using>namespace</Using>

The static modifier imports only the static members and nested types from a namespace:

static using SomeNamespace;

using static System.Console; // Imports a type's methods, like WriteLine.

Some SDKs have implicit using directives. For example, for console applications (Microsoft.Net.Sdk):

To disable implicit imports, add this line to the project file:

<ImplicitUsings>disable</ImplicitUsings>

To use implicit imports but remove a specific one:

<ItemGroup>
	<Using Remove="System.Net.Http" />
</ItemGroup>

The using statement generates a finally statement that calls the Dispose() method on an object that implements IDisposable:

using (FileStream xmlFileStream = File.Create(file.xml)) { … }