Virtual Function In C++

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In this video we will learn about what is virtual function and how to use it in C++.
NOTES:
1. WHY to use virtual function?
a. To achieve dynamic polymorphism. Which is the ability to call Derived class function using Base class pointer or reference.
2. HOW to use virtual function?
a. By declaring function as virtual in Base class and overriding that function in Derived class.
(Function signature should be same in Base and Dervied class)
b. Declaring a function as virtual in Base class is enough, Derived class function need not to be declared virtual.
c. Virtual functions should be accessed using pointer(*) or reference(&) of Base class type to achieve run time polymorphism.
ADITIONAL NOTES:
1. Virtual functions cannot be static and also cannot be a friend function of another class.
2. A class can have virtual destructor but can't have virtual constructor.
3. There are two types of virtual functions in C++.
a. Virtual Function
b. Pure Virtual Function
#cpp #virtualfunction #programming #interviewquestions #softwareengineering #computerscience

Пікірлер: 69

@pinakipb2 3 жыл бұрын

After a long time........... Really appreciate your videos.

@CppNuts 3 жыл бұрын

Thank you so much 😀

@treyquattro 3 жыл бұрын

Always good to see new videos from Rupesh! Virtual is a very important topic in C++

@CppNuts 3 жыл бұрын

Correct!!

@treyquattro 3 жыл бұрын

@Seth Trenton no, no-one gives a shit about your lies and malware

@treyquattro 3 жыл бұрын

@Eufemia Haeber seems to be sockpuppetry and trolling, I think you mean, you pathetic fake

@mockingbird3809 3 жыл бұрын

Great video as always, Cppnuts! ;)

@CppNuts 3 жыл бұрын

Thanks dude...

@mansokash2215 2 жыл бұрын

very good explanation, thank you, keep them like this detailed

@bimalthapaliya7134 3 жыл бұрын

Sir, please make a video on pointer to object and object to pointer! We are getting lots of confusion in that portion! PS- always loved your work! Thank you for this series!

@yashsaxena4634 3 жыл бұрын

Thanks for making it simple.

@CppNuts 3 жыл бұрын

Glad it was helpful!

@ahmedajbna4804 2 жыл бұрын

Thank you so much. I was very confused, now I got it.

@CppNuts 2 жыл бұрын

Welcome..

@Jam18123 3 ай бұрын

very informative, thank you

@rajeshsola1776 3 жыл бұрын

Hi, Thanks for sharing great videos, i think one statement can be fine tuned...Instead of saying virtual functions can be called with pointers and references only (which implies can't be called by objects), we can say that if we call with objects directly it'll go by static binding and won't get benefits of runtime polymorphism (or) to get the benefits of dynamic behavior call by pointer/reference..please see

@CppNuts 3 жыл бұрын

Thanks man, but did i said this? I think i always added dynamic word with that line.

@raghuj7097 3 жыл бұрын

Super...after a long time...we are happy to see

@CppNuts 3 жыл бұрын

Thanks..

@abhinavkumar562 3 жыл бұрын

I hope that you will continue the dsa series...

@CppNuts 3 жыл бұрын

Sure man..

@amitpaunikar3408 3 жыл бұрын

After long time.....good explanation

@CppNuts 3 жыл бұрын

Thanks..

@ManishPatel-dj7eb 3 жыл бұрын

Nice informative video, It explains all details in easy way. thanks Q1. Which editor you are using ?

@Vicky-xi9ns 3 жыл бұрын

Thanks for your c++ series

@CppNuts 3 жыл бұрын

Glad you like them!

@abhaybajpai9469 2 жыл бұрын

Very Informative video....thanks a lot.....again!!!😁

@CppNuts 2 жыл бұрын

Welcome..

@mohammadjadidi233 3 жыл бұрын

Really appreciate your videos....

@CppNuts 3 жыл бұрын

Thanks..

@chitranshsaxena59 3 жыл бұрын

Hey, nice video, maybe you can also explain about vtables and stuff

@ArjunArjun-vw5fq 3 жыл бұрын

congrats for 28k.

@CppNuts 3 жыл бұрын

Thanks bro..

@ravishsga 3 жыл бұрын

Good to see you back Rupesh :) Just one question in which scenario we need to call the derived function with the base class pointer? Why we are making the base class pointer point to the derived object?

@CppNuts 3 жыл бұрын

If you want to create an array of different objects you can make their parent common and have array of pointers of those different object and do some operations on a single array. Let me know if this is not clear, actually I wanted to explain this also in video that why do we need that but I didn't actually find the good example for this.

@hritik4807 2 жыл бұрын

@@CppNuts not clear , can you make a video :)

@bhupeshpattanaik7150 3 жыл бұрын

Thanks ☺️ .... Please guide for competitive coding using CPP

@CppNuts 3 жыл бұрын

Sure dude.. Let's complete virtual topic first.

@bhupeshpattanaik7150 3 жыл бұрын

@@CppNuts ya please that soon ..... Very curious to start

@prasadsolleti3870 5 ай бұрын

Sir please explain one real time example code in virtual function and pure virtual function

@sureshonteru4609 3 жыл бұрын

Hi Rupesh Thanks a lot for the video , still I have a doubt why Base * b = derived () It's calling base class method, what happens it's storing derived class address but it's calling base class method ,what happens inside and compile time . can you explain

@hunnybunny4723 10 ай бұрын

So what exactly is the use of this virtual functions concept? In what way is it useful in the real world scenario? We can call derived function by creating derived object ryt, what exactly the need of calling through the base class pointer?

@priyaldesai8290 2 жыл бұрын

Hi, Thank you for sharing the video. Can you please share the link for following vptr and vtable video as well.

@CppNuts 2 жыл бұрын

I prepared notes to teach but i lost it somehow and still i didn't feel like redoing that notes, that was like so much hard work.. Hope i may find courage to redo it and shoot the vid.

@prishaphotography9063 3 жыл бұрын

Nice👍

@CppNuts 3 жыл бұрын

Thanks ✌

@AJAYKUMAR-gl1vx 2 жыл бұрын

class Base{public: virtual f(){}}; class Derived:public Base{public: f(){}}; int main(){Derived d; Base b=d; d.f(); return 0;} Here f() will be early binding or late binding??

@adityavaste3732 2 жыл бұрын

That was so an amazing tutorial... But I have one doubt, that why we are saying it as "Run-Time Polymorphism", bcz compiler can easily decide which function he has to call, as we are using "virtual" keyword there, So, at a compile-time, he knows that, "We don't have to call the function in the base class bcz it is using virtual keyword, and we have to call the function from the derived class with the same name", that's simple........... he can easily decide at a compile-time, why he goes with run-time?

@CppNuts 2 жыл бұрын

But it can call base class function also.. that's the point. Base pointer can contain either base object or derived object if it is containing derived object in that case it will call derived class function or if it is holding base class object then it will call base class function. That's why it is run time behaviour because base pointer can contain either base object or derived object so we really don't know no what object it is going have till run time.

@vvpChannel3112 3 жыл бұрын

What if we have a data member in base class lets say float f=1.2; So, can we access b->f iff Base *b = new Derived ?

@CppNuts 3 жыл бұрын

Yes..

@sharath5796 3 жыл бұрын

u have to declare that data member as protected ig

@AJAYKUMAR-gl1vx 2 жыл бұрын

Hi 😊 Can you please explain, why pointer or reference variable is required for late binding?

@CppNuts 2 жыл бұрын

Because late binding itself tells that I will be available later, and what ever comes later you have to work on that and this later thing is handled using pointer or reference, because later only these two make sense. In case of static (current, not the late) meaning you already have the object on which you will work.

@AJAYKUMAR-gl1vx 2 жыл бұрын

@@CppNuts Thank you 😊

@shirishareddy2795 3 жыл бұрын

why can only achieve polymorphism(virtual function) through pointers or references,but not through object assignment. pl z solve my doubt sir

@ranjanrajesh08 Жыл бұрын

Hi Rupesh, i tried coding using reference concept for virtual polymorphism…it is not working exactly the same way…i mean to say using reference if i try to call the fn…by removing virtual keyword in base class, then also last overridden fn gets called instead of base class fn

@CppNuts Жыл бұрын

Give me the code plz.

@ranjanrajesh08 Жыл бұрын

@@CppNuts hey Rupesh…my mistake…i must have been doing some mistake…I tried to run the code again and i see it is working as expected…Thanku Rupesh😊

@jilmon3498 2 жыл бұрын

Virtual table ?? Video?

@lifeisacelebration7233 3 жыл бұрын

Volume is bit less for all videos.

@CppNuts 3 жыл бұрын

Correct, i try to avoid noise, so it become like that, i will work on this sound issue. Thanks..

@lifeisacelebration7233 3 жыл бұрын

@@CppNuts thank you for all the tutorials

@CppNuts 3 жыл бұрын

You are welcome..

@vishalchoudhary2913 Жыл бұрын

9:50 Please correct you can give body to pure virtual function.

@CppNuts Жыл бұрын

Yes we can give body to pure virtual function.

@nikhilkhatri9721 Жыл бұрын

*I don't want to become animal!!*

@CppNuts Жыл бұрын

Good

@Mani--ck3xc Жыл бұрын

hi @CppNuts i am getting this error cannot find virtual: No such file or directory , c:/users/mani.chaitanya.konka/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/12.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find virtual: No such file or directory c:/users/mani.chaitanya.konka/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/12.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find function: No such file or directory