What is namespace in c# with example

What is namespace in c#

A namespace is a collection of classes and Using is keyword to import namespace(Using is just like #include in C-Language), their are various inbuilt namespaces available in C#.net.

1. Data --is a namespace for database connectivity.

2. A System(Root namespace) is the namespace that consists of several classes for a basic operation like Console.

3. A namespace is consist of several of the class

4. MVC is a namespace which consists of several class for defining the webpage by MVC.

List of most common namespaces used in c# 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Services;

using System.Data;

using System.Web.Script.Serialization;

using System.Diagnostics;

using System.Net;

using System.IO;

using System.Text;

using Microsoft.Ajax.Utilities;

using System.Configuration;

System:

The system is a root namespace in c#, whenever we write any code we need to use using System; namespace to get all the basic programming features.

How to use User Defined Namespace in c#

In c# language we can define our own namespace by using the keyword namespace Let's understand the concept of a user-defined namespace.

Suppose, there is a class bank and is available in the group1 namespace, see the example.

using System;  // root namespace
namespace group1   // user-defined namespace
{
{
     public class bank
     {
            // function and variables
     }
}

Now, If you want to access the bank class, you need to have included the namespace where you are going to accessing it (in another class/project).

using System;  // root namespace

using group1   // accessing the user-defined namespace

namespace group2   // user-defined namespace
{
     public class employee

     {

             public static void Main()

             {
              bank obj = new bank ();// Displays 'My Class'
             } 

     }
}

What is class and the architecture of class in c#

Class is a keyword. Class allow creating a user-defined data type within a class, we can have multiples of variables Every type of variable plays a significant

role by developing  the application
For Example:

 >When we declare the class in c#, a variable can have 5 kinds of scope.

1. Private
2. Public
3. protected
4. Internal
5. Protected internal

Access Modifier in c#

If we declare a class in c# by default scope of the class is  Internal.

If we declare the variable within the class by default scope is private.

Whenever write a class in c# by default it is child class or derives class inherited from an object class(base class)

   using System;

  class Employee      //(Employee is the custom type that is define by me)

    {

         int a;

         string name;

         public static void Main()

         {

         }

    }

Whenever In the above example we can see that we have a class called Employee and it doesn't have any access modifier it means that it is an internal class.

And using System; is a root namespace.