C# Tutorial 9 Abstract Class Polymorphism

In this part of my C# tutorial we'll be covering Abstract Classes, Virtual Methods, Abstract Methods, Override, Base Classes, Is, As, Casting and more about Polymorphism.

For best results take notes on the cheat sheet provided above as you watch and leave any questions you have.

Thank you to Patreon supporters like the following for helping me make this video

jaryd remillard : instagram: @distant_admiration
@kyleaisho
@thetwistedhat
vjFaLk

[montenague]

Derek I just want to chime in and say that your videos are the best around - I am pivoting careers right now into c# backend dev and your tutorials have kept me productive within my team.
What I am trying to say is keep it up, you are changing lives.

[ScottZion]

Great stuff Derek! As a newbie learning OOP and c#, I can't express how much your videos have helped. Big thanks...

[mattshu]

Stopping by to say thanks—you’re the reason I made it off my programming plateau I was stuck on for years as a teen.

[SunnyApples]

Thank you for the video! These are very much appreciated!
They brighten my day each time I see them in my inbox!

[masoud]

great tutorial on c#, a treasure you cannot even find in treasure island
thanks Derek

[colin-campbell]

A lot of people are here because you’re the first result without a thick Indian accent.

[bartonpaullevenson]

Good one again. I'm learning a lot from these. I mostly program in VB, but there's a lot of demand for C# out there, so I want to know it.

[junkiecosmonaut]

Good tutorial, coming over from Java, I find C# very similar.

[yummyEnchilada]

I like that I can follow along with these video's because the code is zoomed in, no Indian accent either, lol., thank you

[mr.logicpants]

Derek, thank you for sharing this. I am always interested in how other developers approach things and you are well spoken and use examples that are easy to understand. You may want to think about teaching a course on Pluralsight or one of the other code teaching sites. I have a subscription to Pluralsight and you teach better than many of the people who taught the classes i have seen on there. In any case, thanks for sharing your knowledge.

[nailin]

@8:35 you created an array of Shape that contains Circle and Rectangle and both are derived class. Does this mean Shape array simply hold the address for its derived objects? If that is not the case, how does the compiler knows how much memory to reserve for the array since the derived objects consume more memory and may have different sizes. To be more specific, say I declare a Shape array with a capacity of 3 then how much memory does the each element consume?

[TheEsisia]

Great video Derek. I've learned a lot from your videos. Just noticed one thing. Shouldn't the Name property in the Shape class be protected instead of public? In the way that it is right now, one can actually name a circle object: "rectangle".

[tiangkingming]

Hi Derek, this is a good video. Thanks for your sharing.
I have one question, why do we able to create an abstract class instantiate (e.g. shape[] ) ? Is it because of the content is its sub classes?
Thanks again.

[aychtooo]

Derek I heard you are getting into video game design so I have a few things to tell you. First of all I urge you to check out Extra Credits, and if you have time Mark Brown, Extra Credits has video of how the game industry works, problems and solutions modern games have, and important principles that video games need to follow to be considered more fun. Mark Brown has video where throughout the entire video he takes an example of a principle of game development from an existing game, and talks about how and why it works, instead of what Extra Credits does which is talking about the main ideas of these principles (although in my opinion Extra Credits is a better channel and is more worth your time). I also have a question: why does half the world hate video games?

[fourdaysdead]

What does it mean inconsistent accessibility, why Circle class cannot be public?

[FacePalmProduxtnsFPP]

"Well hello internet!" He says.. and I suddenly feel the urge to yell back at my phone, "Well hello to you too! Voice of a strange yet very knowledgeable and helpful man on the Heh heh

[berzurkfury]

would have liked to of seen a bit more on casting, around its behavior specifically.
Circle cir = shape as Circle; will attempt to cast but not throw and exception
Circle fails = will attempt to cast and if it fails it will throw an exception

[mau_lopez]

Hello Derek, great video again! Just one question (I must be missing something), if abstract classes are meant to not be instantiated, what is the difference between them and static classes? Thanks

[abdel-rahmanmagdygado]

hi Derek l have learned the basic of python . what do you think should l learn python GUI or django?

[hazemhussien]

hey derek at the end of this tutorial what programs will i be able to make ? ( maybe give examples about famous programs or games that are made with C# )