C# Namespaces

Namespaces in C# are used to organize too many classes so that it can be easy to handle the application.

In a simple C# program, we use System.Console where System is the namespace and Console is the class. To access the class of a namespace, we need to use namespacename.classname. We can use using keyword so that we don't have to use complete name all the time.

In C#, global namespace is the root namespace. The global::System will always refer to the namespace "System" of .Net Framework.

Example

Let's see a simple example of namespace which contains one class "Program".

snippet

using System;
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello Namespace!");
        }
    }
}

Output

Hello Namespace!

Using fully qualified name

Let's see another example of namespace in C# where one namespace program accesses another namespace program.

Example

snippet

using System;
namespace First {
public class Hello
{
    public void sayHello() { Console.WriteLine("Hello First Namespace"); }
}
}
namespace Second
{
    public class Hello
    {
        public void sayHello() { Console.WriteLine("Hello Second Namespace"); }
    }
}
public class TestNamespace
{
    public static void Main()
    {
        First.Hello h1 = new First.Hello();
        Second.Hello h2 = new Second.Hello();
        h1.sayHello();
        h2.sayHello();

    }
}

Output

Hello First Namespace Hello Second Namespace

Using keyword

Let's see another example of namespace where we are using "using" keyword so that we don't have to use complete name for accessing a namespace program.

Example

snippet

using System;
using First;
using Second;
namespace First {
public class Hello
{
    public void sayHello() { Console.WriteLine("Hello Namespace"); }
}
}
namespace Second
{
    public class Welcome
    {
        public void sayWelcome() { Console.WriteLine("Welcome Namespace"); }
    }
}
public class TestNamespace
{
    public static void Main()
    {
        Hello h1 = new Hello();
        Welcome w1 = new Welcome();
        h1.sayHello();
        w1.sayWelcome();
    }
}

Output

Hello Namespace Welcome Namespace