1. Namespaces Group related C# features into categories
Contain code that can be reused
.NET framework library (FCL) contains many namespaces
Must be referenced with using directive in order to be used
Example: Console feature is in
namespace System

2. C# namespaces- allow you to group classes as a collection
 Standard C# .NET Framework library has namespaces: System and System.Linq …
Also hierarchical: System.Collections.Generic
WHY?
Guarantee uniqueness of class names
NOTE: no logical relationship between namespaces … just physical

3. USING namespaces
Can use all classes within namespace and all public classes in other classes as long as you
1. Qualify
System.Collections.ArrayList
2. using namespace
using System.Collections;
3. using a class in a namespace
using MyNameSpace.MyClass;

4. careful with name conflicts
EXAMPLE
using System.DateTime;
using System.Net.HttpRequestHeader;
//both have Date class
SOLNs:
using System.DateTime.Date; to use this one
use qualifiers if you need both.

5. HOW TO ADD A CLASS TO A namespace
Create a new project of type Class Library
Add code defining public class
MyNameSpace {
class MyClass{} }
Compile to create a .dll file

6. HOW TO ADD A CLASS TO A namespace
In project using class:
Add a reference to the class library in an app
Right click on project in solution explorer and select Add Reference
In code using class
Specify a using directive
using MyNameSpace;

7. Directory structure
Put source files of namespace in subdirectory of project directory
. (projectdirectory)
ManipCN.java
MyNumericsNameSpace
ComplexNumber.cs
Build in project directory

8. TO SHARE namespaces
Need to have special directory. I called mine C:\Csharp\classes
NOTE: Csharp is my BASE directory
I put files ComplexNumber.java in C:\Csharp\classes\
I put ManipCN.cs in C:\Csharp