Partial Class in C# with example, What is the use of partial class (Oops Programming)

Usage of Partial Class in Object Oriented Programming

Introduction:

In my previous articles we saw the oops programming concepts like Access Modifiers in C#,what is the use of Abstract Classes,Why we need sealed classes,Static Classes and Static Class Members in C# and various articles on WPF and Asp.Net.

           Now in this tutorial we will see what is partial class in C#, why use of partial class,difference between partial class and class in C#.

Description:

What is partial Class in C#? Difference between partial class and class?

In Object Oriented Programming it is possible to split the definition of a class or a struct, or an interface over two or more source files.Each source file contains a section of the class definition, and all parts are combined when the application is compiled. So a partial class is one which looks like a class except it is defined in multiple files. To Split a class definition , use partial keyword modifier.

Why we use partial classes:

• This feature allows us to write single class file into multiple files so that multiple programmers can work at a time.
• When working with automatically generated source, code can be added to class without having to recreate the source file.

Partial Class in C# with example:

 Take a class and name it as part1.cs in your console application project and write below.

namespace OOPSProject { partial class Parts { public void Method1() { Console.WriteLine("Method 1"); } public void Method2() { Console.WriteLine("Method 2"); } } }

Take another class and name it part2.cs and write below code.

namespace OOPSProject { partial class Parts { public void Method3() { Console.WriteLine("Method 3"); } public void Method4() { Console.WriteLine("Method 4"); } } }
To test these two classes take another class and name it as testpart.cs and write below code .

namespace OOPSProject { class TestParts { static void Main() { Parts p = new Parts(); p.Method1(); p.Method2(); p.Method3(); p.Method4(); Console.ReadLine(); } } }

Key Points while writing Partial Classes in C#:

• All the parts of the class must be defined within the namespace( same assembly or same module).
• All the parts must be used with partial keyword.
• All the parts must be available at compile time to form the final class.
• All the parts must have the same accessibility level, such as public, private,protected
  and so on.
• if any part of the class is declared as abstract then whole type is considered as abstract in the same
  manner for the sealed.
• If any part is declares a base type, then the whole type inherits that class.
• partial modifier is not available on delegate or enumeration declarations.
   

Conclusion:

I hope you got an idea on how to and when to use partial classes with example and what precaution we should take care while writing partial classes. I would love to take feedback from my readers about my this writing.

 Related Articles:

• Access modifiers or Access Modifiers in C#.
• Abstract classes in c# and Uses of Abstract Classes.
• Sealed classes and Sealed methods in c#.
• Static Classes and Interview Questions.
• WPF Architecture.
• Asp.Net Ajax Tutorial.
• Asp.Net Validation Controls tutorial.