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Namespaces (C# Programming Guide)

Namespaces are heavily used in C# programming in two ways. First, the .NET Framework uses namespaces to organize its many classes, as follows:

System.Console.WriteLine("Hello World!");

System is a namespace and Console is a class in that namespace. The using keyword can be used so that the complete name is not required, as in the following example:

using System;
Console.WriteLine("Hello");
Console.WriteLine("World!");

For more information, see using Directive (C# Reference).

Second, declaring your own namespaces can help you control the scope of class and method names in larger programming projects. Use the namespace keyword to declare a namespace, as in the following example:

namespace SampleNamespace
{
    class SampleClass
    {
        public void SampleMethod()
        {
            System.Console.WriteLine(
              "SampleMethod inside SampleNamespace");
        }
    }
}

Namespaces have the following properties:

  • They organize large code projects.

  • They are delimited by using the . operator.

  • The using directive obviates the requirement to specify the name of the namespace for every class.

  • The global namespace is the "root" namespace: global::System will always refer to the .NET Framework namespace System.

For more information, see the C# Language Specification. The language specification is the definitive source for C# syntax and usage.

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