C# Namespaces

In the C#, namespaces are used to organize and provide multiple classes, structs, interfaces, enums and delegates. It use to control the scope of methods and classes in larger .Net programming.

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

A namespace can have following types as its members:

• Namespaces (Nested Namespace)
• Classes
• Interfaces
• Structures
• Delegates

C# namespace using keyword example

using System; //this is using keyword 
namespace NameSpaceExample//this is created namespace
{  
    public class Program 
    {  
       public static void Main(string[] args)  
        {  
          Console.WriteLine("Hello FindAndSolve");  
        }  
    }  
}  

Output

Hello FindAndSolve

C# Define a Multiple Namespaces

In c#, you can define and access multiple namespaces in your application with using keyword.

Example

using System;  
namespace FirstNameSpace {  
public class FirstHelloClass 
{  
    public void sayHello() { Console.WriteLine("Hello First Namespace"); }  
}  
}  
namespace SecondNameSpace  
{  
    public class SecondHelloClass 
    {  
       public void sayHello() { Console.WriteLine("Hello Second Namespace"); }  
    } 

}  

public class TestNamespace 
{  
    public static void Main()  
    {  
        FirstNameSpace.FirstHelloClass objFirst = new FirstNameSpace.FirstHelloClass();  
        SecondNameSpace.SecondHelloClass objSecond = new SecondNameSpace.SecondHelloClass(); 
        objFirst.sayHello();  
        objSecond.sayHello();  
    }  
}  

Output

Hello First Namespace

Hello Second Namespace

Nested Namespaces in C#

In the c#, a namespace under another namespace  is called a Nested Namespace. The nested namespace classes and their class or member can be accessed by using the dot (.) operator like as given below.

Syntax

namespace MainNameSpace{
    namespace NestedNameSpace{
    // Nested Namespace Code
    }
}

Example

using System;
using CustomNameSpace.Nested;
namespace FindAndSolve
{
    public class Program
    {
        public static void Main(string[] args)
        {
             Welcome w = new Welcome();
             w.GreetMessage();
        }
    }
}

namespace CustomNameSpace {
      namespace Nested
      {
          public class Welcome
          {
              public void GreetMessage()
              {
                  Console.WriteLine("Welcome to FinsAndSolve");
              }
          }
      }
}

Output

Welcome to FinsAndSolve