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.

C# namespace example

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

1. using System;  
2. namespace ConsoleApplication1  
3. {  
4.     class Program  
5.     {  
6.         static void Main(string[] args)  
7.         {  
8.             Console.WriteLine("Hello Namespace!");  
9.         }  
10.     }  
11. }  

Output:

Hello Namespace!

C# namespace example: by fully qualified name

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

1. using System;  
2. namespace First {  
3. public class Hello  
4. {  
5.     public void sayHello() { Console.WriteLine("Hello First Namespace"); }  
6. }  
7. }  
8. namespace Second  
9. {  
10.     public class Hello  
11.     {  
12.         public void sayHello() { Console.WriteLine("Hello Second Namespace"); }  
13.     }  
14. }  
15. public class TestNamespace  
16. {  
17.     public static void Main()  
18.     {  
19.         First.Hello h1 = new First.Hello();  
20.         Second.Hello h2 = new Second.Hello();  
21.         h1.sayHello();  
22.         h2.sayHello();  
23.   
24.     }  
25. }  

Output:

Hello First Namespace
Hello Second Namespace

C# namespace example: by 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.

1. using System;  
2. using First;  
3. using Second;  
4. namespace First {  
5. public class Hello  
6. {  
7.     public void sayHello() { Console.WriteLine("Hello Namespace"); }  
8. }  
9. }  
10. namespace Second  
11. {  
12.     public class Welcome  
13.     {  
14.         public void sayWelcome() { Console.WriteLine("Welcome Namespace"); }  
15.     }  
16. }  
17. public class TestNamespace  
18. {  
19.     public static void Main()  
20.     {  
21.         Hello h1 = new Hello();  
22.         Welcome w1 = new Welcome();  
23.         h1.sayHello();  
24.         w1.sayWelcome();  
25.     }  
26. }  

Output:

Hello Namespace
Welcome Namespace