virtual vs override vs new keywords in c#

13/04/2015 VirtualvsOverridevsNewKeywordsinC#

http://www.csharpcorner.com/UploadFile/2072a9/virtualvsoverridevsnewkeywordsincsharp/ 1/7

Ask a Question

READER LEVEL:ARTICLE

This article explains the basic differences between the three most frequently used andconfusing keywords in C#.

Virtual vs Override vs New Keywords in C#By Abhishek Jaiswal on Sep 08, 2014

The purpose of writing this article is simple; to provide a simple and fresh demonstration of the basicdifferences between these three frequently used and confusing keywords in C# with some referenceexample. This article is purely for the beginner in C#.

Outlines

OverviewIntroduction

Virtual KeywordOverride KeywordNew Keyword

Demo ExamplesSample ImplementationNew KeywordVirtual and Override KeywordMethod Overloading + Riding

Key PointsConclusions

Overview

In this article I'll explain how virtual, override and new keywords vary by taking some set of examplesrespectively some sort of functionality.Finally there will be some key points to remember about all these 3 keywords.

Introduction

This introductory part will provide a brief introduction of all these 3 keywords. So here they are.

Virtual Keyword

The Virtual keyword is used for generating a virtual path for its derived classes on implementingmethod overriding. The Virtual keyword is used within a set with an override keyword. It is used as:

01. //BaseClass02. classA03. {04. publicvirtualvoidshow()05. {06. Console.WriteLine("Hello:BaseClass!");07. Console.ReadLine();08. }09. }

Override Keyword

The Override keyword is used in the derived class of the base class in order to override the base classmethod. The Override keyword is used with the virtual keyword, as in:

01. //BaseClass02. classA03. {04. publicvirtualvoidshow()05. {06. Console.WriteLine("Hello:BaseClass!");07. Console.ReadLine();08. }09. }10. 11. //DerivedClass12. classB:A13. {14. publicoverridevoidshow()15. {16. Console.WriteLine("Hello:DerivedClass!");

01 Lotus Notes to SharePoint MigrationUsing QUEST02 Google+ Authentication in ASP.Net

03 Basics of AngularJS: Part 1

04 Angular JS Filter, Sorting andAnimation Using MVC and WCF Rest05 How to Retrieve All Users From theGroup in SharePoint Using REST API06 Creating Dynamic DataGridView UsingHelper Class07 Terminologies in MVC: Part 1(ViewData, ViewBag, TempData)08 MVC AngularJS and WCF Rest ServiceFor Mind Reader Quiz09 Angular JS Shopping Cart Using MVCand WCF Rest Service10 Basic Terminology of SQL Server

View All

TRENDING UP

Follow@csharpcorner 14.6Kfollowers

In Focus MUST READ: Authors How to improve your Writing Skills

Contribute

Lotus Notes to SharePoint Migration ... C#CornerSearch

10946 5 3

FindusonFacebook

C#Corner

87,746peoplelikeC#Corner.

Like

TECHNOLOGIES ANSWERS BLOGS VIDEOS INTERVIEWS BOOKS NEWS CHAPTERS CAREER ADVICE JOBS



17. Console.ReadLine();18. }19. }

New Keyword

The New keyword is also used for polymorphism but in the case of method overriding. So what doesoverriding means? In simple words we can say that we are changing what the base class does for thederived class.

It is implemented as:

01. classA02. {03. publicvoidshow()04. {05. Console.WriteLine("Hello:BaseClass!");06. Console.ReadLine();07. }08. }09. 10. classB:A11. {12. publicnewvoidshow()13. {14. Console.WriteLine("Hello:DerivedClass!");15. Console.ReadLine();16. }17. }

Demo Example

Sample Implementation

Here's a simple implementation in C# without using any keywords. Do you think it will run fine, orwill it show a runtime or compiletime errors? Let's see:

01. usingSystem;02. usingSystem.Collections.Generic;03. usingSystem.Linq;04. usingSystem.Text;05. 06. namespaceGenerics07. {08. classA09. {10. publicvoidshow()11. {12. Console.WriteLine("Hello:BaseClass!");13. Console.ReadLine();14. }15. }16. 17. classB:A18. {19. publicvoidshow()20. {21. Console.WriteLine("Hello:DerivedClass!");22. Console.ReadLine();23. }24. }25. 26. classPolymorphism27. {28. publicstaticvoidMain()29. {30. Aa1=newA();31. a1.show();32. Bb1=newB();33. b1.show();34. Aa2=newB();35. a2.show();36. }37. }38. }

Output Window



It is showing some sort of output. That means there is neither a runtime nor a compiletime error.But it will definitely show a warning in Visual Studio. So do you want to know what it is and how toremove it?

Keep reading and you will go through that.

Warning Message

Here's the warning message that you will get:

Solution

The solution of this problem is already in the warning. Just read it carefully and you will get that. Yesyou got that right, for removing that warning we need to use the new keyword.

In the next sample demo example is showing you a simple demo snippet and implementation of thenew keyword. I hope now you will be getting why we are using the new keyword in here.

New keyword | Method Overhiding

Here's a simple snippet of method overriding. So just go through it and guess the output:

01. usingSystem;02. usingSystem.Collections.Generic;03. usingSystem.Linq;04. usingSystem.Text;05. 06. namespaceGenerics07. {08. classA09. {10. publicvoidshow()11. {12. Console.WriteLine("Hello:BaseClass!");13. Console.ReadLine();14. }15. }16. 17. classB:A18. {19. publicnewvoidshow()20. {21. Console.WriteLine("Hello:DerivedClass!");22. Console.ReadLine();23. }24. }25. 26. classPolymorphism27. {28. publicstaticvoidMain()29. {30. Aa1=newA();31. a1.show();32. Bb1=newB();33. b1.show();34. Aa2=newB();35. a2.show();36. }37. }38. }



Output Window

Explanation

The procedure goes something like that:

Virtual and Override Keywords | Method Overriding

This is a simple example of method overriding. Just go through it and guess the output again andalso try to differentiate between the previous snippet and this snippet.

01. usingSystem;02. usingSystem.Collections.Generic;03. usingSystem.Linq;04. usingSystem.Text;05. 06. namespaceGenerics07. {08. classA09. {10. publicvirtualvoidshow()11. {12. Console.WriteLine("Hello:BaseClass!");13. Console.ReadLine();14. }15. }16. 17. classB:A18. {19. publicoverridevoidshow()20. {21. Console.WriteLine("Hello:DerivedClass!");22. Console.ReadLine();23. }24. }25. 26. classPolymorphism27. {28. publicstaticvoidMain()29. {30. Aa1=newA();31. a1.show();32. Bb1=newB();33. b1.show();34. Aa2=newB();35. a2.show();36. }37. }38. }

Output Window



Explanation

The flow goes something like that:

Overriding + Hiding | Together

This snippet shows how both of these methods can work together in a same snippet. So just gothrough this and guess the output.

01. usingSystem;02. usingSystem.Collections.Generic;03. usingSystem.Linq;04. usingSystem.Text;05. 06. namespaceGenerics07. {08. classA09. {10. publicvirtualvoidshow()11. {12. Console.WriteLine("Hello:BaseClass!");13. Console.ReadLine();14. }15. }16. 17. classB:A18. {19. publicoverridevoidshow()20. {21. Console.WriteLine("Hello:DerivedClass!");22. Console.ReadLine();23. }24. }25. 26. classC:B27. {28. publicnewvoidshow()29. {30. Console.WriteLine("AmHere!");31. Console.ReadLine();32. }33. }34. 35. classPolymorphism36. {37. publicstaticvoidMain()38. {39. Aa1=newA();40. a1.show();41. Bb1=newB();42. b1.show();43. Cc1=newC();44. c1.show();45. Aa2=newB();46. a2.show();47. Aa3=newC();48. a3.show();



49. Bb3=newC();50. b3.show();51. }52. }53. }

Output Window

Explanation

The flow goes something like that:

Key Points

I am providing some key points about these keywords by taking a reference of method overloading andoverriding concepts, since these keywords are used in these mechanisms.

Virtual and Override

Used in polymorphism implementationIncludes same method name and same paramsUsed in method overridingIt is also called runtime polymorphismCauses late binding

New

It is also used in polymorphism conceptIncludes the same method name and different paramsUsed in method overridingIt is compiletime polymorphismCauses early binding

Conclusion

So did you like it, I hope you so!

Well I tried to provide just a brief sketch of these keywords, that are very necessary for a beginner in C# aswell as in OOP. If you have a good understaind of OOP then you can take any objectoriented language inyour pocket.

So just go through OOP first and then C# and if you are facing any problem then feel free to ping ormessage me.

Happy coding, Cheers!



RELATED ARTICLES

Hosted By CBeyond Cloud Services

2015 C# Corner. All contents are copyright of their authors.

Abhishek JaiswalAGeek!

Personal Blog:http://geeksangle.ghost.io/

Rank42

1mReaders

GoldMember

2Times

Virtual Method in C# Difference Between Override and New KeywordExplained Step-by-Step

Difference Between Override and New Keywordin C#

Var vs Dynamic Keywords in C#Method Overriding in C#

Function Overriding and Its Impact DuringObject Initialization

Const vs Readonly in C#Look at Load Testing in Visual Studio 2012

Differences Among Method Overriding, MethodHiding (new Keyword) and Method Shadowingin C#

OOPS Concepts and .NET Part 2: Inheritance,Abstraction, & Polymorphism

COMMENTS 5of5

Sep 09, 2014

634 1 0 0 0 Post Reply

good explanation

Gyan Parkash

Sep 09, 2014

4 12.8k 4.2m 0 0 Post Reply

Good work Abhishek.

Dinesh Beniwal

Sep 09, 2014

392 268 62.9k 0 0 Post Reply

nice article

Manju lata Yadav

Sep 09, 2014

325 389 130.5k 0 0 Post Reply

Good One....

Divya Sharma

Sep 09, 2014

42 3.6k 1m 0 0 Post Reply

Thank u guys! :)

Abhishek Jaiswal

Type your comment here and press Enter Key....

COMMENT USING

Facebooksocialplugin

Addacomment...

Commentusing...

MVPs MOST VIEWED LEGENDS NOW PRIZES REVIEWS SURVEY CERTIFICATIONS DOWNLOADS

CONTACT US PRIVACY POLICY TERMS & CONDITIONS SITEMAP REPORT ABUSE

PHOTOS CODE SNIPPETS CONSULTING TRAINING STUDENTS MEMBERS MEDIA KIT ABOUT US LINKS IDEAS

virtual vs override vs new keywords in c#

Documents

used andconfusing keywords

new keywordthe new keyword

virtual path

articlethis article

thederived class

rest api06

wcf rest05

tempdata08 mvc angularjs