Copying and Copy Constructors in C++
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- เผยแพร่เมื่อ 20 มิ.ย. 2024
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In this video we're talking about copying in C++. Copying objects (and data) is commonly necessary in C++, and to properly facilitate that for our custom types, we need to add something called a copy constructor, which performs a deep copy of our object, if one is necessary. Something called a "(copy) assignment operator" is also sometimes necessary, but we'll talk about that in another video. Copying is not free however, and can slow down your program, so try and avoid it if possible.
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finally a series on youtube I don't have to put on 2x speed lol
Agree. Watching on 1.5x speed. Can't go higher.
I am really curious If this is filmed at that speed. It is insanely fast
Up until episode 30 or so I was watching at 2x speed just so i can get back to the opengl series
I'm at 50% speed and finally I understand he speaks english...
Still watching at 2x speed. Otherwise he would be too slow
We're so lucky this C++ series are free x)
Until he realises he can buy a t-rex with his course money if it wasnt free.
then again asking 10$ for this course wouldn't be all that much
Laurentiu Stefan it is for some people who just want to learn
absolutely
@@hitlard5305 exactly what i was thinking as well, regardless im sure he gets a lot more support not asking and seeing what happens.. patreon is there for a reason..
The speed you go is perfect, most tutorials are too slow. I lose interest and get nothing. This isn't overly fast and can be followed, also you can tell you really know your stuff so if just flows. Good work, thanks.
I am worried, he's too fast
You can play this at x0.75 or at x1.25 up to your personal preference. I am a bit ashamed to say but I might need x0.5 to get some understanding of the matter :)
@@marindraganov8765 If I don't understand something, I keep repeating it
@@this_is_mac While loop?
@@pierfrancescopeperoni
while(understanding == false){
ReplayVideo();
}
7:25 thank you for the solution for fixing random garbage at the end of a dynamic char array.
I came here looking for copper
But found gold
17:48 Little did he know it would take him 3 More Years...
lol! me too, I actually watched the l, r values first
lol
As someone who learned C and Java at Uni, and is trying to learn C++, this was something that I didn't realize was important until recently. I think this helped solidify a few things in my head.
I assume you're going to talk about Move constructors soon too.
Yes, we'll get into move semantics eventually. :)
Ever since I stumbled across your channel , it has become a routine to watch one or more of your videos . I don't know it's like an addiction . You have such a clarity in your understanding at such an early age . Awesome and good luck.
Thank you so much. I've heard of this copy constructor topic many times and never understood it. You're the first person to explain WHY it's useful and the problem it solves.
I've been rewatching this series just for fun, and as always the videos are excellent, informative, and concise.
Thanks!
I recently found these C++ videos on YT. They're excellent. Thanks for the effort Cherno.
Even though I've already been through most of this stuff, I love watching your videos 'cause they're such a great way to remind me of some details I've forgotten, provide another viewpoint on some of these topics and deepen/solidify my understanding of them.
If it weren't for these videos I'd probably have a whole lot of "backtracking" to do at certain points but just watching one of your videos every day or two really helps rearrange all this stuff in my head in some kind of orderly manner ^^
Keep up the good work man, this series is basically the best online resource ever to do that sort of thing
Pretty much the same for me. Another benefit is, that I learn better ways to explain stuff, sometimes new team members will not be very good at C++, so I can use some of the examples in these videos when they have problems.
So true. I thought I have understood all about copy constructor until I sit down and watch this video again and then I go "Ahhhhh so that is how it works"
the best video for deep and shallow copy
you really got concept clarity in each video
really appreciate your work for society!
love your work and explaining
Thank you. I knew vaguely about copying, but thanks to you I understand it clearly now. I'm also watching other videos from the C ++ series.
this cleared concept of shallow vs deep copy, copy constructor, along with operator overloading & importance of pass by reference, brilliant!
This is one of the greatest content I have seen on C++ copy constructors...Thanks Cherno
This was a really comprehensive tutorial. Thank you!!
I am new to C++ and your tutorial just save my life, thanks a lot!
Excellent example, really clear and concise, well done.
Thanks for making a good example. It cleared Copy constructor, Deep/Shallow copy and reference.
The most perfect and not unliked video series on youtube. U rule my Career propably, at least you have a signifant influence about my clarity. I have to thank u
no kidding, i havent seen many but these are high quality c++ videos
Great job with this series!!
Charno - No char for you
Such a fantastic lesson! Second time to review this.
ive said this before, and ill say it again.. this is one of the most informative code channels on youtube.
this is the most interesting episode in the series :)
Nice explanation, awesome . Excellent work.
Great summary, excellent, simple examples
This literally gave me the solution to an issue I was having related to dynamically creating pointers inside of a base class. I narrowed down the issue that the same location in memory was being deleted twice, but I didn't know the next step. Then this video got reccomend almost as if youtube just knew lol. I'll have to implement the copy constructor and try it out.
Thank you so much for helping with that piece of code for 14:32
Thank you. That was super helpful!
How can I be so information-attended and creative in writing code and remembering it without facing any obstacles? I mean u're so fast, so good, keep going brother.
Great explanation. Thank you!
Just want to say thanks for preparing me for my job interview.
Thank You. This was an awesome video on c++ concepts.
Congrats on 500K subs man !
Thank you, very well explained.
Man, this series is good. Fast, to the point and makes me feel like I've just sniffed 20 grams of speed.
Great video!
You sir are a very good, thanks for these series!
thanks alot man, you are the best. for me this is heavy stuff alr, but you make me so easy to understand.
Amazing explanation ❤️
The action is starting!
hey youre really good at explaining things cheers!
Awesome Video .. All concepts well explained...!
Fantastic content!!!!
probably the best cpp video it covers so many things haha
TheCherno has taught me well; I saw the copies coming with the PrintString() function as he always passes by const ref to avoid this exact thing
Thank you Charno, I have learned a lot from you : )
Thank you so much Yan for these amazing videos. I don't have the money to support you on Patreon but one day I will definitely do it. Love from India :)
That is awesome video!
There is no need to separately copy the NULL terminator in the constructor, you could've just used the m_Size + 1 in the memcpy, just like in the copy constructor, since if the string wasn't properly terminated, the strlen wouldn't work properly as well.
yes that worked for me to instead of his way, thanks :)
Agreed
Kinda glad he did it wrong though, the extra steps helped me understand it better and reading the comments gives one expertise.
Yeah I got confused about this exact thing.
Thanks for this video! It is amazing.
Greetings from Germany!
haha ChArno! Bro you are hilarious! Really like the series!!
C++ is a great language.
I admire sir. Bijarn Stroustrup as well as sir. Dennis Ritchie.
I love the humor this man has.
this video is still helpful in 2022. Thanks a bunch
youre a great teacher, thanks
best video explaining copy and deepcopy
Very helpful. Also note that you will make a copy when you return a String object
Awesome, Thanks!
¡Happy day, Cherno!
you said at 1:24 "so what I'm trying to tell you is always pass your objects by const reference" and I misunderstood that, trying to pass pointers to arrays by reference... it was a 1-hour nightmare fixing the resulting bugs
Nice one :) i get the ideas of what that actualy does far better Then in highscool explanation
Great episode.
this is very good information
Nice explanation.
Awesome video
Very nice tutorial
Fantastic!
This was a quality lesson
Great video
just excellent!
detail is rich, pace is balanced, a sub is gained
Creation of "Reference(&)" is one of the good improvement of C++ comparing with C.
Reference gives more "memory efficiency" to us.
Also if the function accept reference you don't have to check if the argument is null or not
This is very arguable. References are just dereferenced pointers and there's not a lot of difference between them. In fact, pointers have a lot more power than references because they can be null, changed and mutated. References never can.
really helpfull stuff :)
Deep Object.. Shallow Copy.. I saw that look! So many great analogies to make lol
This is a lifesaver
Just WoW
Thank you
Ah, looks like I have reached my first soft cap. Everything up to here was pretty easy to understand for me but I'm starting to feel that I have not understood the preceding topics well enough to follow this 100%. I get the problem you are trying to demonstrate but the stuff around it is a bit too shaky still. I will have to rewatch some of the previous videos and practice some more and I'm sure I'll understand this better because your explanation is done very well :)
You talk really fast and put so much information in just 5 seconds. For a beginner I find Your channel intimidating to watch as i really just understand the first minute and everything comes after slips away
Your tutorials are amazingly well done, and helped me a lot, thanks man!
For some reason, at my old place of work work our style guide was against passing by reference but to use pointers instead. I'm not sure if they determined it was actually faster, or because they preferred more "C" style code. I don't think the advice was much heeded, though.
THanks Charno
Personal Notes:
-Shallow copy becomes a problem for heap-created objects, not for stack allocated objects(might needs check)
-Deep copy is performed by adding copy constructor. After writing copy constructor, you can use “entity1 = entity2” for deep copying
-Explained pass by value vs pass by reference. It is safe to use const reference for the function not to be able to modify the object.
You have my sub.
The only exception that I can think of at the moment to the pass by const ref advice is with primitive types that can be created on the stack.(x86 specific) And that is because the speed of creating, using, and deleting stack frames is pretty close to the minimum lag physically possible due to a combination of cache coherence, registers, and the way the stack pointer works. In some cases the optimizer will not even assign a memory location to a stack primitive, it may live entirely within a cpu register; and deleting a frame is only a matter of decrementing the stackpointer which is generally a one CPU-cycle operation. Still its a pretty narrow case where a program would spend a substantial amount of time creating and deleting primitives.
Along with the usual advice to not optimize too much until after getting the logic correct and profiling to find that big O chunk of code. (A bit of consideration for runtime efficiency is warranted during the initial draft just to avoid huge structural changes later on, just don't spend a bunch of time on it.)
Hey Yan, I'm following your channel for about a few days, and I'm loving your videos about C++ and I wanna know if you have a Github of projects in C++ or maybe you know of some Githubs with projects in C++, I wanna look at the code to learn more programming technics.
Shin Lim does a good job teaching C++.
You are talking so fast. but your style is very clear. Thanks for sharing.
Awesome BUT so fasssst! I have to watch the video many times to better understand. Anyways you are still my professor
I love you Charno
Thanks
Any idea when you'll be able to get to move semantics? BTW great job with this c++ series!
That cactus, watch out for your hands ;) thanks for explaining!
I just tried this technique
and it work for object on the heap too..
so now I realized const reference is used when the object we want to use
does not need to be changed..
although it is const it's value can be assigned to another variable like std:: vector or array
Way to go Charno
thanks Charno.
@The Cherno. Pls, pls, pls make a Cherno branded T-shirt. I wanna but its to support you cuz I love what you do and I want others to know about you. the best way for me to spread the good word about your channel is with a T-shirt!
is it suitable to simply use 'unsigned int' to cater for functions like strlen which return size_t. I believe most implementations define size_t as a typedef of unsigned int.
God, I wish my lecturer explained this like you did...