Tutorial 5:Namespaces

Namespaces are C# program elements designed to help you organize your programs. They also provide assistance in avoiding name clashes between two sets of code. Implementing Namespaces in your own code is a good habit because it is likely to save you from problems later when you want to reuse some of your code.
// Namespace Declaration
using System;

// The Portal-management Namespace
namespace Portal-management
{
// Program start class
class NamespaceCSS
{
// Main begins program execution.
public static void Main()
{
// Write to console
Console.WriteLine("This is the new Portal-management Namespace.");
}
}
}
It shows how to create a namespace. We declare the new namespace by putting the word namespace in front of Portal-management. Curly braces surround the members inside the Portal-management namespace.

Nested Namespace
// Namespace Declaration
using System;

// The Portal-management Tutorial Namespace
namespace Portal-management
{
namespace tutorial
{
// Program start class
class NamespaceCSS
{
// Main begins program execution.
public static void Main()
{
// Write to console
Console.WriteLine("This is the new Portal-management Tutorial Namespace.");
}
}
}
}

Another Way to create Namespace using "." operator i.e Portal-management.tutorial
// Namespace Declaration
using System;

// The Portal-management Tutorial Namespace
namespace Portal-management.tutorial
{
// Program start class
class NamespaceCSS
{
// Main begins program execution.
public static void Main()
{
// Write to console
Console.WriteLine("This is the new Portal-management Tutorial Namespace.");
}
}
}
It shows another way of writing nested namespaces. It specifies the nested namespace with the dot operator between Portal-management and tutorial.

Calling Namespace Members: NamespaceCall.cs
// Namespace Declaration
using System;

namespace Portal-management
{
// nested namespace
namespace tutorial
{
class myExample1
{
public static void myPrint1()
{
Console.WriteLine("First Example of calling another namespace member.");
}
}
}

// Program start class
class NamespaceCalling
{
// Main begins program execution.
public static void Main()
{
// Write to console
tutorial.myExample1.myPrint1();
tutorial.myExample2.myPrint2();
}
}
}

// same namespace as nested namespace above
namespace Portal-management.tutorial
{
class myExample2
{
public static void myPrint2()
{
Console.WriteLine("Second Example of calling another namespace member.");
}
}
}

Another way to calling namespaces with the help of "using" keyword or with the Alias Directive:

// Namespace Declaration
using System;
using Portal-management.tutorial;

// Program start class
class UsingDirective
{
// Main begins program execution.
public static void Main()
{
// Call namespace member
myExample.myPrint();
}
}

// Portal-management Tutorial Namespace
namespace Portal-management.tutorial
{
class myExample
{
public static void myPrint()
{
Console.WriteLine("Example of using a using directive.");
}
}
}

With the Alias Directive:
// Namespace Declaration
using System;
using csTut = Portal-management.tutorial.myExample; // alias

// Program start class
class AliasDirective
{
// Main begins program execution.
public static void Main()
{
// Call namespace member
csTut.myPrint();
myPrint();
}

// Potentially ambiguous method.
static void myPrint()
{
Console.WriteLine("Not a member of Portal-management.tutorial.myExample.");
}
}

// Portal-management Tutorial Namespace
namespace Portal-management.tutorial
{
class myExample
{
public static void myPrint()
{
Console.WriteLine("This is a member of Portal-management.tutorial.myExample.");
}
}
}

In summary, you know what a namespace is and you can declare your own namespaces. If you don't want to type a fully qualified name, you know how to implement the using directive. When you want to shorten a long namespace declaration, you can use the alias directive. Also, you have been introduced to some of the other namespace members in addition to the class type.