Virtual Functions in C++ 

If you live your life without recognising levels of impact and absorbing some, you're not going to get anything done.

I was just kidding, but the topic of optimization in programming is very interesting to me. ;)

Some additional runtime costs are acceptable to make the COST of actually programming it smaller. And hay, people even use python to program which gives you a heavy runtime penalty compared to C/C++...

Interesting.

Let's say, I just touch your cheeks using a fingertip and then I slap you. Both are impacts. The first 1 will just hurt you mentally (some feeling of awkwardness) but the second 1 will hurt you both physically and mentally). You may ignore the 1st one and move on with your life, but you won't be able to forget about the second one for quite a while. I hope I have made my point.

thanks man, this is exactly what I was wondering

thx :)

thanks man!

Thanks a lot.

also inheritance in C++ really clears up the class Player : public Entity

Thanks for explaining. Now it all makes sense.

Thank you for your detailed explanation!

Thanks, this was really helpful. There is one more thing that was not explained before (as far as I can recall). In the constructor of the player class, he uses a constant string "name", which he passes by reference (first, I don't understand why this has to be a constant or a reference) and then he goes on to add the colon and m_name(name). I think I have seen in some other tutorial series that this is the way to load a value into a constant but I am not sure now.

thank u bro, love u every much

So what's "Player(const std::string& name) : m_Name(name) {}" exactly? Could u give me a keyword of this stuff to search? I have no idea what it is and how to search it for details.

This is fax, i just tried it 🤣

Excellent comment. I'm having an error now which mentions the vtable and I think I know what's going on now thanks to this explanation . Thanks!

Thanks for sharing!

Doesn't it matter how big your vtable is though?

Dereferencing the function pointer can cost you 1000 instructions, because RAM has a high latency.

@@ronensuperexplainer depends. Couldn't one develop a prefetcher for this problem to reduce memory latency?

I don’t know if it’s this guys videos that influence my feelings but I feel like C++ is the most intuitive programming language I’ve ever used. I feel like the newer higher level languages abstract things away to the point where they actually miss their goal of being easier, and wind up being much more confusing because there is so much going on behind the scenes that you never really know what exactly your code is doing.

@@jscorpio1987 +1

@@jscorpio1987 hell no

whew... that's a relief :D

Thanx man

ty

Can confirm, just revisited this and it makes so much more sense

Lightslinger Deadeye many thanks for your explanation!

There's no _real_ practical difference between the two, however there is a difference. Since m_Name is a class member which has the type std::string (which is stack-allocated), it will actually be instantiated twice in your second example (firstly with an empty string, and secondly copied from the name parameter), but only once in your first example (via the constructor's intiailiser). Definitely going to be a video on this in the future. :)

TheChernoProject thanks :)

+TheSunscratch Also you cannot use the first approach if the data member is static.

Does the compiler (with -O2 or -O3 ) optimize it so that there is no difference eventually?

Me too

You must unlearn what you have learned.

Rewording content in summary form is actually a great way to learn and reinforce knowledge 👍🏽

Yes, that will be covered in the vtable video. Late binding doesn't _really_ exist in C++ since everything must be known at compile time, and the vtable essentially just allows dispatching to a number of preset values (that are contained in the table), not to _anything_ which would be the case with late binding.

Right on. Thanks.

ikr its confusing where he keeps on jumping everywhere i cant keep up

Certainly, this is not a topic for a newbie... virtual function is a complex feature of class heritance that I don't think there is an easy way to explain to people who have never coded anything in their life. This guy is obviously an expert and knows what he is talking about because he must have been programming for years.

That's true! I kept on pausing the screen to get it

Yup. Many of these will work on pre C++11, but most are C++24, especially the later videos, which are strictly C++14 and up

These videos started out so exceptionally great but it seems he has grown weary of this subject now, rushing through them and using unexplained code all the time.

Go review the video on Inheritance.. That should help you understand it better.

@@loveboat wat

There is Zero problem with this video. If you don't get it then you haven't actually practiced inheritance enough to learn why we needed the virtual functions in the first place. Just watching videos will never get you anywhere in programming. You will have to actually write the code, test it with all possible conditions you can think of, try to do illegal stuff and then understand why it is not working, is the only way you can truly learn any topic.

@@deleater I think he is not refering to virtual functions. Cherno introduced many other subjects in this video without explaining them, but all these are explained in future videos, so the only thing to take out of this video is the type "Virtual" subject

Because the *new* keyword dynamically allocates memory and returns a pointer to the address of that allocated memory, hence why we need a pointer type. Check out my video on pointers if you haven't already, and I will definitely be making a video on memory allocation in the future.

I will just add that in Java classes are by default reference types, while in C++ everything is value type, so if you need to refere to the same value, then you need to use pointers. So you can use same class definition as reference or value type. For example if you have new class Vector (position) , and you pass it to function as Vector (by value) or as Vector * ( as pointer only). If you embed Vector in Entity you can embed entire Vector or only a pointer to Vector.

There is no Nuremberg Funnel. Use textbooks. Play around with code. These videos just can give you deeper insights.

Thanks for that timely and apt reminder! You got this all of you!!

hey I hope you found answers your questions but this maybe helpful for someone else , for the first question: In c++ there is a way to initailize a variable with { } without using = operator , so for example int x{0} , y {10} (you basically did x=0, y=10;) and also you can use this way of initalization for constructors in this case , Player(const std::string& name) :m_Name{name}{ } basically initalize m_Name to the value of name it is actually the same thing with Player(const std::string& name) { m_Name = name; }, depends on your style of coding for the second quesiton I think you mean this parameter in the Player constructor , (const std::string& name ) so here & says it is a referance to the variable not pointer , it is widely used for parameters to strings in order not to create a temporary string value and copying its value to it like void getName( string name) {m_Name = name; } because here you basically created a name variable and you passed a value to it like "Cherno" and you copy it to the m_Name, this means an extra garbage spaces right but if you use & then there wont be any name value created, so directly "Cherno" or , whatever you pass , it will be directly assigned to m_Name, I hope its clear and you can watch reference video or see more examples on it :)

@@enes5345 thank you!

@@maolin7866 you're welcome and also I am sorry I have learnt recently something new that I didn't know that in c++ initializing variables using initializer list( intiliazing variables after : ) is different than to initialize variables in the constructers body , when you initialize variables using initializer list what c++ do is it directly creates and initializes variables in the memory with the values that you have passed but doing this in the body of the constructers, c++ creates those variables in the memory and than assign them those values, this doesn't make much difference with intgrrs doubles or so but if you pass any object to the constructers like in copy constructers than using initializer list makes difference its faster as far as I know ( If you guys know sth diff pls tell us ) ,and one more thing initilazing vatiables using ( ) , and {} also different even in normal initialization like int a{}; different than int a(); again this might not make alot differencr for the int like variables it makes for objects creation , do in this way Point(string& name) : m_Name {name} { //Body } Thanks for your comment so that I could find a way to correct myself 😅🤗

@@enes5345 Thank you for your explanation!