Hope you guys enjoyed the video! A few notes: - to be clear, each program/process on our computer has its own stack/heap - each thread will create its own stack when it gets created, whereas the heap is shared amongst all threads
So if your program is using multiple threads and there is memory which is created by one thread and needs to be read by another, for example, this memory would need to be allocated on the heap?
Yes. But that is really not good practice. When one thread is using something in heap allocated memory it has to lock the access to that memory until it doesn't need it anymore. So you really need to avoid using shared resources when using multiple threads. Threads are meant to do their own thing independent from other threads. You can use it to keep to keep track of like progress of all threads but continous access to resource is performance hit.
Objects like Enemies in a game should always be created on the heap right? Are the variables of this object then also on the heap or will they be on the stack?
the variables inside the object are created inside the object's "memory space". So if you have an Enemy with an x and a y, it will allocate 8 bytes (2 ints = 2 * 4 bytes) and store the x and y in that space.
I honestly fucking hate it when people make 'you taught better in 15 mins than my university was able to in 4 years' comments on these videos. Like bitch please it doesn't take 4 years to learn these you just haven't been paying attention
@@quicksilver5413 I didn't learn more in 15 minutes than in 4 years but this particular concept was not explained... my c++ teacher was absolute garbage. My java teacher was great, and a lot of that knowledge transfers over but... meh. java...
I’m a Software Engineer, and my first SWE position was as a C++ developer which I learned predominantly from Cherno. I have an EE education, but I learned more from Cherno watching TH-cam than I did in my Intro to C++ and Data Structures and Algorithms in C++ sequence in college. The Cherno is legit folks, but if you really wanna learn, you gotta start at the beginning of the playlist and go straight through watching EVERY VIDEO and coding along. C++ can be a frustrating language to learn, but if you learn C++ first, it’s cake learning ALL OTHER C-like languages. You’re the man Cherno!
I like how you show why something is “expensive” or not very optimal instead of just saying it. You actually open the memory view or disassembly which is super useful! Thanks for the videos, they’re amazing!
*My takeaways:* 1. Both stack and heap memory are in RAM 0:47 2. How to allocate stack and heap memory 2:55 3. Stack memory allocation *stacks* data in the memory *in a row* and it is very fast 4:45 4. Heap memory allocation doesn't 7:49 5. Heap memory allocation needs to be freed manually by using "delete", whereas stack memory allocation is freed once the code is out of the current scope 8:47 6. How heap memory, "new" and "delete" work 10:27, allocating memory on the heap is slow
For all C# developers: "new" does not mean, that it will be allocated on the Heap (for C# program) MyClass c = new MyClass(); // Allocated on the Heap MyStruct s = new MyStruct(); // Allocated on the Stack (in most cases) That doesn't mean that structs are ALWAYS allocated on the Stack! Just most of the times. It depends. Read about "stackalloc" keyword and about "Span" and "ReadOnlySpan". They are great!
This is by far the most complete lecture/tutorial whatever, I have seen in a very long time (possibly ever). You explained everything very clearly, demonstrated and tested them, yet did that all in 20 minutes. I am honestly surprised that this video doesn't have hundreds of thousands of views because you deserve that. Wish you the best!
Its been 5 years since you uploaded and still it is one of the BEST video on the internet. Yours is a C++ Goldmine. could you please talk about your learning pedagogy of new things and especially C++. How did you gain so much clarity ?
Thanks! One thing worth mentioning: We use heap for allocation during runtime and stack for allocation during compile time. It was mentioned somewhat in the video but I think it should be more emphasized.
hey cherno, your explanation of stack vs heap is amazing, no other youtube has evern been able to explain like this. ive come across heap and stack so many times but never got to really understand untill i watched your video today. thanky you so much!
Oh boy! I found a C++ video from you and now I'm stuck with video recommendations of your series. I appreciate that, but it's 22:30 and I wanna sleep... Seems like I wont
This is A+ content. For someone trying to learn to code there is a lot here and I will be re-watching this a couple of times and playing with the memory view in Visual Studio. Thanks.
The stuff that I learned in this one single video is actually insane. like, I knew about most of the stuff that he said, but since all of it was taught to me over various courses, and bits and pieces at a time, I never really could figure out how it all fit in together...This such a wonderful explanation!! All of it is starting to kind of make sense now....damn lol
Keystrokes would have been an absolute godsent in this. I know IDE use isn't the topic of such an essential instructional video, but you're doing so much basic stuff that it would be really easy to follow along with both the theory and the mechanics of writing and moving around your code that one might want to set up and get used to.
MAGISTER DIXIT...! I am no programmer but I have had basic lessons in C almost 30 years ago and now I am strugling to master at least the basics of C#, which I find sometimes a bit confusing and with a lot of rules. Sometimes I get some comfort watching basic C ++ videos, especially those that are very well explained and that go right to the point like yours.
Great video! Heap memory is a really complex topic.... It took me a long time to figure out how it works when I was writing my own memory manager! Thanks a lot for this!😃
This was a very interesting video. Please, make more videos about the way C++ works. I am looking forward to seeing your video about CPU cache optimisation. Thank you, Cherno, love your vids.
This is the first video I've watched and I wanted to say - Really well done! Such a top notch explanation. I'm subscribing for sure. Thanks again for taking the time to make these videos
This was a really helpful video, thank you SO much. I appreciate that you show WHY the dynamic memory operations are more expensive and how it can be a performance boost to use the stack. So essentially, if you want something to have a longer lifetime, or if it's of a large size, then it's worth using the Heap, but if you're making a small simple variable that won't exist for a long time, it makes more sense to just use the stack, yeah?
Hi Cherno, nice explanation. Probably main point is not covered here. 1. Each function has its own stack area and not shared with other functions. Whereas heap is shared among all functions(within a thread as you said in a comment). 2. main use of heap is to allocate memory for pointer that is accessed across the functions. because once the functions scope is over, all stack variables are deallocated.
Cherno, your tutorials are always great. I love that you pay attention to what you say. You always choose your words so that YOUR AUDIENCE understands what you say, and not so that you make sense to yourself. Thank you for the good work and congratulations. I am sure when you become worldwide famous these videos will get a lot more views. I have a question for you: How did you get to point that you know the material well enough to teach it? Who/What is **your** teacher? Other than sporadically making google searches and stumbling on documentation pages, do you regularly read books on C++? Do you constantly take classes? Do you continuously engage in competitions that keep your edge sharpe? How are you so good? I am not asking how are you productive. I just wander how do you keep this volume of knowledge in your head in such an order that becomes transferable to others. If I don't refresh something for a month (give or take) I surely forget it ... xD
@@nobytes2 I believe he's not asking for a magic formula. He wants to know the materials / instructors / methods The Cherno uses to learn and retain the vast amount of comp sci knowledge he teaches us. Practice and experience is correct, but *how* does he practice? Is it through competitions, work, reading books, classes, etc. Hope this helps
I love how I get a good in depth explanation of stack & heap. Dare I say better explained than my proff. And at the end of the video I go. Wow! I have the same couch!
Hi, you could make a video explaining your way of structuring C++ projects: the way you separate your headers from source files, the way you organize your includes (precompiled header stdafx.h vs #ifndef guards), etc. What do you think? You're doing a great work, I've been learning a lot in your channel! Thanks!
@@patrikjankovics2113 This does not always work sadly. When you start having a medium or large-sized project (1M lines ) it will start to fail for some reason sadly, happened to me many times, thus using #ifndef
@@patrikjankovics2113 #pragma once still can't prevent against including multiple headers within the same project because it excludes based on file system identity
Hi Cherno, Could you maybe take a video about exceptions, and why you don't like them, how to avoid them and best practices. Also a good topic to talk about is unit testing and do you write tests in parallel with your development. Thanks for everything your doing here.
i have been programming c++ for almost 7 years now , what makes you unique among other youtube channels or tutorials is that you are really so deep in learning and teaching the concepts . keep going man you are awesom !
Thanks @cherno for making these videos. Few follow-up Qs: 1. How many CPU cycles does Heap allocation take for each of the examples you talked about in the video above? 2. Can you start a series on OS basics like different types of memory, how it all works at the OS level etc. Thanks! :)
This video is really easy to understand!! I didn't know that allocating memory in heap is such a heavy work, and didn't know why it's heavy. You showed me the way to ensure the reason, looking into the assembly code. I'm gonna consider using Visual Studio...
One case for allocating memory on the heap is when one doesn’t know the size of data at compile time. STL containers are actually allocated on the heap internally because they grow in size dynamically when the preallocated size is not enough. So if you declare a vector on the stack, it is actually using the heap.
Pal, thanks a lot! It is like putting me in a new dimension with my coding! Now I have a vague idea why my projects work the way they do! Coming from Python/C# background this video is an eye opener! EDIT: Typo.
Thanks Cherno ! I was wondering if sometime you could dive into Windows Forms Applications using Visual C++ :-). I'm really enjoying your tutorials man !
Neil Tsakatsa Don’t think that we will ever use this api same with WinForms you probably should look at C++/Winrt wich is more native than the CLR version wich has an ugly syntax and is very slow compared to Nativ C++.
Great explanation. But I think we're missing an important difference between stack and heap memory. The size of stack memory to allocate is set at compile time whereas the size of heap memory is may be set in run time. Stack memory is more easy to manage and heap memory is more flexible (and maybe more efficient since actually may allocate just as much memory as you need when actually running your program).
@Artem Katerynych In the example he used int value; and int *hvalue; both exist on the stack while the value of int *hvalue exist on the heap.. That is from what I understand him saying.
@4:04 Vector3* hvector = new Vector3(); /*Meaning variable called "hvector" which also an object to the structure called "Vector3" is stored in the stack. "hvector" also creates another variable of it's type in the heap. So, "hvector" is also a pointer.
Hope you guys enjoyed the video! A few notes:
- to be clear, each program/process on our computer has its own stack/heap
- each thread will create its own stack when it gets created, whereas the heap is shared amongst all threads
So if your program is using multiple threads and there is memory which is created by one thread and needs to be read by another, for example, this memory would need to be allocated on the heap?
Are you going to cover multiple threads because I had I look and it seems simple but could get complicated
Yes. But that is really not good practice. When one thread is using something in heap allocated memory it has to lock the access to that memory until it doesn't need it anymore. So you really need to avoid using shared resources when using multiple threads. Threads are meant to do their own thing independent from other threads. You can use it to keep to keep track of like progress of all threads but continous access to resource is performance hit.
Objects like Enemies in a game should always be created on the heap right?
Are the variables of this object then also on the heap or will they be on the stack?
the variables inside the object are created inside the object's "memory space". So if you have an Enemy with an x and a y, it will allocate 8 bytes (2 ints = 2 * 4 bytes) and store the x and y in that space.
How is it that none of my teachers explained any of this during my whole bachelors degree.... this is brilliant! Thank you so much!
Bad college ? 😅
not really, when you learn something for the first time, you might have been overwhelmed.
I honestly fucking hate it when people make 'you taught better in 15 mins than my university was able to in 4 years' comments on these videos. Like bitch please it doesn't take 4 years to learn these you just haven't been paying attention
@@quicksilver5413 I didn't learn more in 15 minutes than in 4 years but this particular concept was not explained... my c++ teacher was absolute garbage. My java teacher was great, and a lot of that knowledge transfers over but... meh. java...
tanks
You are insanely efficient in explaining complex material, wow..., kudos.
Moreover he has very nice sweat pants! Kudos for that as well
100%
Facts and he actually helps see the bigger picture instead of dwelling on definitions
I am pretty sure he speeds up his videos as well :-)
I’m a Software Engineer, and my first SWE position was as a C++ developer which I learned predominantly from Cherno. I have an EE education, but I learned more from Cherno watching TH-cam than I did in my Intro to C++ and Data Structures and Algorithms in C++ sequence in college. The Cherno is legit folks, but if you really wanna learn, you gotta start at the beginning of the playlist and go straight through watching EVERY VIDEO and coding along. C++ can be a frustrating language to learn, but if you learn C++ first, it’s cake learning ALL OTHER C-like languages. You’re the man Cherno!
That’s awesome! I’m a computer science major looking for my first C++ gig. Can you tell me more about how you got it? Thank you!
@@mauricecooper9880 Hello, I'm also looking for a job. Have you found one?
I like how you show why something is “expensive” or not very optimal instead of just saying it. You actually open the memory view or disassembly which is super useful! Thanks for the videos, they’re amazing!
Happy birthday cherno!!!
This comment have 281 likes But 0 replies (except me)
@@mokshithpb7991 2 now
@@paulu2862 3 now
@@projectvibe1226 4 now
@@chauffeur1560 5 now
*My takeaways:*
1. Both stack and heap memory are in RAM 0:47
2. How to allocate stack and heap memory 2:55
3. Stack memory allocation *stacks* data in the memory *in a row* and it is very fast 4:45
4. Heap memory allocation doesn't 7:49
5. Heap memory allocation needs to be freed manually by using "delete", whereas stack memory allocation is freed once the code is out of the current scope 8:47
6. How heap memory, "new" and "delete" work 10:27, allocating memory on the heap is slow
For all C# developers: "new" does not mean, that it will be allocated on the Heap (for C# program)
MyClass c = new MyClass(); // Allocated on the Heap
MyStruct s = new MyStruct(); // Allocated on the Stack (in most cases)
That doesn't mean that structs are ALWAYS allocated on the Stack! Just most of the times. It depends.
Read about "stackalloc" keyword and about "Span" and "ReadOnlySpan". They are great!
This is by far the most complete lecture/tutorial whatever, I have seen in a very long time (possibly ever). You explained everything very clearly, demonstrated and tested them, yet did that all in 20 minutes. I am honestly surprised that this video doesn't have hundreds of thousands of views because you deserve that. Wish you the best!
Its been 5 years since you uploaded and still it is one of the BEST video on the internet. Yours is a C++ Goldmine. could you please talk about your learning pedagogy of new things and especially C++. How did you gain so much clarity ?
"Stored in the caysh"
caysh money dawg
I understood cage first, then caysh, then i understood that he actually means cache
Dude I read that and spit out my drink I can't stop laughing
a couple of cæche misses
Thanks! One thing worth mentioning:
We use heap for allocation during runtime and stack for allocation during compile time. It was mentioned somewhat in the video but I think it should be more emphasized.
hey cherno, your explanation of stack vs heap is amazing, no other youtube has evern been able to explain like this. ive come across heap and stack so many times but never got to really understand untill i watched your video today. thanky you so much!
I think this is my favorite video so far. I always wondered about the stack and heap differences. This is such a good explanation!
Oh boy! I found a C++ video from you and now I'm stuck with video recommendations of your series. I appreciate that, but it's 22:30 and I wanna sleep... Seems like I wont
same
Damn.
It's 22:35 here.
Awesome COINCIDENCE
Finally, you are back, your video always great, thank you !!
This is A+ content. For someone trying to learn to code there is a lot here and I will be re-watching this a couple of times and playing with the memory view in Visual Studio. Thanks.
The stuff that I learned in this one single video is actually insane. like, I knew about most of the stuff that he said, but since all of it was taught to me over various courses, and bits and pieces at a time, I never really could figure out how it all fit in together...This such a wonderful explanation!!
All of it is starting to kind of make sense now....damn lol
This stuff is all great man. All of your C++ videos have been amazing so far.
Keystrokes would have been an absolute godsent in this. I know IDE use isn't the topic of such an essential instructional video, but you're doing so much basic stuff that it would be really easy to follow along with both the theory and the mechanics of writing and moving around your code that one might want to set up and get used to.
MAGISTER DIXIT...!
I am no programmer but I have had basic lessons in C almost 30 years ago and now I am strugling to master at least the basics of C#, which I find sometimes a bit confusing and with a lot of rules. Sometimes I get some comfort watching basic C ++ videos, especially those that are very well explained and that go right to the point like yours.
I had an interview question about this that I totally dropped the ball on. Thank you for this overview!
Great video! Heap memory is a really complex topic.... It took me a long time to figure out how it works when I was writing my own memory manager! Thanks a lot for this!😃
Very clear and easily accessible explanation, even the explaining with asssembler was just really supporting understanding.
This was a very interesting video. Please, make more videos about the way C++ works.
I am looking forward to seeing your video about CPU cache optimisation.
Thank you, Cherno, love your vids.
A trendy looking programmer that makes good quality programming tutorials on TH-cam that doesn't use a mac?
Respect.
This is the first video I've watched and I wanted to say - Really well done! Such a top notch explanation. I'm subscribing for sure. Thanks again for taking the time to make these videos
This was a really helpful video, thank you SO much. I appreciate that you show WHY the dynamic memory operations are more expensive and how it can be a performance boost to use the stack.
So essentially, if you want something to have a longer lifetime, or if it's of a large size, then it's worth using the Heap, but if you're making a small simple variable that won't exist for a long time, it makes more sense to just use the stack, yeah?
Hi Cherno, nice explanation.
Probably main point is not covered here.
1. Each function has its own stack area and not shared with other functions.
Whereas heap is shared among all functions(within a thread as you said in a comment).
2. main use of heap is to allocate memory for pointer that is accessed across the functions. because once the functions scope is over, all stack variables are deallocated.
Cherno, your tutorials are always great. I love that you pay attention to what you say. You always choose your words so that YOUR AUDIENCE understands what you say, and not so that you make sense to yourself. Thank you for the good work and congratulations. I am sure when you become worldwide famous these videos will get a lot more views.
I have a question for you: How did you get to point that you know the material well enough to teach it? Who/What is **your** teacher? Other than sporadically making google searches and stumbling on documentation pages, do you regularly read books on C++? Do you constantly take classes? Do you continuously engage in competitions that keep your edge sharpe? How are you so good?
I am not asking how are you productive. I just wander how do you keep this volume of knowledge in your head in such an order that becomes transferable to others. If I don't refresh something for a month (give or take) I surely forget it ... xD
This is like asking a musician how she/he gets good lol. There's no freaking magic formula, is just practice and experience.
@@nobytes2 I believe he's not asking for a magic formula. He wants to know the materials / instructors / methods The Cherno uses to learn and retain the vast amount of comp sci knowledge he teaches us. Practice and experience is correct, but *how* does he practice? Is it through competitions, work, reading books, classes, etc. Hope this helps
@@nobytes2 he just asking for tools
I love you! YOU ARE SUPER HELPFUL !!!!!!!! KEEP THIS PASSION ON MAKING VIDEO. YOU ARE TALENTED
I love how I get a good in depth explanation of stack & heap. Dare I say better explained than my proff.
And at the end of the video I go. Wow! I have the same couch!
Hi, you could make a video explaining your way of structuring C++ projects: the way you separate your headers from source files, the way you organize your includes (precompiled header stdafx.h vs #ifndef guards), etc.
What do you think?
You're doing a great work, I've been learning a lot in your channel! Thanks!
#pragma once I think, instead of ifndef guards.
@@patrikjankovics2113 This does not always work sadly. When you start having a medium or large-sized project (1M lines ) it will start to fail for some reason sadly, happened to me many times, thus using #ifndef
@@patrikjankovics2113 #pragma once still can't prevent against including multiple headers within the same project because it excludes based on file system identity
Hi Cherno,
Could you maybe take a video about exceptions, and why you don't like them, how to avoid them and best practices.
Also a good topic to talk about is unit testing and do you write tests in parallel with your development.
Thanks for everything your doing here.
I learn so much over this channel thank you for the hard work!
I just nailed an interview question because of this and other videos. Thanks so much.
i have been programming c++ for almost 7 years now , what makes you unique among other youtube channels or tutorials is that you are really so deep in learning and teaching the concepts . keep going man you are awesom !
7 years of typing and you don't know where the shift button is?
Thank you so much for this content. It's been very useful for me.
Clear, ,fluent and to the point explanation, thanks.
Many thanks for your effort and your very clear explanantions.
Thank you for this video. I have been confused about stacks and heaps. You helped me so much. Time to practice 🙌🏽🙌🏽
I loved the way you explained them through the code, thank you truly!
Thanks @cherno for making these videos. Few follow-up Qs:
1. How many CPU cycles does Heap allocation take for each of the examples you talked about in the video above?
2. Can you start a series on OS basics like different types of memory, how it all works at the OS level etc. Thanks! :)
THANK YOU SOOO MUCH MAN. VERY HELPFUL VIDEO, LOVED IT
wow, this video is wonderful! It answers a lot of my questions. Thank you Cherno!
Happy Birthday & Thank you very much for your great content! :)
Best content i found....Crazy, how it is simple and detailed 🔥.. Thank you
This video is really easy to understand!! I didn't know that allocating memory in heap is such a heavy work, and didn't know why it's heavy. You showed me the way to ensure the reason, looking into the assembly code. I'm gonna consider using Visual Studio...
You are awesome Cherno! Thanks for your clear explanations!
This video helped me a ton with interview questions, thank's so much!
Its was super useful video. Thanks and Gratitude!!
I just enjoy u talking, very easy to absorb
You're the best man excellent explanation, thank you
Excellent refresher for me. Subscribed.
amazing and very clear video!
Very nice and informative, I am kinda addicted to your videos gj.
Amazing explanation! Thank you!!
Thank you for this really great content, Cherno!
Thank you so much for your serie Cherno, I always learn alot watching you
Happy holidays to you and your friends/family :)
Next level videos. Thank you!
Your a very clever guy. I find your videos extremely helpful
Thanks a lot man your videos are so helpful , keep going 💙💙
You are a king. Excellent explanation, thank you.
This is the best explanation video about Stack vs Heap I ever seen, Thanks man.
One case for allocating memory on the heap is when one doesn’t know the size of data at compile time. STL containers are actually allocated on the heap internally because they grow in size dynamically when the preallocated size is not enough. So if you declare a vector on the stack, it is actually using the heap.
amazing, explained really well and in a clean way
Thanks for explaining this sooooo clearly and in an easy way!!!!! very useful!
Just subscribed. Enjoyed the content. 😇
Sick bro
I enjoyed the video. Thank you!
dude, you're awesome! I've learned it like a piece of cake!
Very well explained, very good examples!
Pal, thanks a lot! It is like putting me in a new dimension with my coding!
Now I have a vague idea why my projects work the way they do! Coming from Python/C# background this video is an eye opener!
EDIT: Typo.
your videos have been very helpful to me. I hope things are going good for you Cherno :-)
The stack within the function is as a 2nd heap that is tiny and it will be automatically deallocated when it leaves its scope.
Amazing video! Thanks. I just subbed.
words cant describe this video thanks for helping
still such an amazing and practical video now it's 2021.
thanks dude, good explanation
Awesome video !!!
Wow. This guy is next level and then some. 🔥
Thanks Cherno ! I was wondering if sometime you could dive into Windows Forms Applications using Visual C++ :-). I'm really enjoying your tutorials man !
Neil Tsakatsa Don’t think that we will ever use this api same with WinForms you probably should look at C++/Winrt wich is more native than the CLR version wich has an ugly syntax and is very slow compared to Nativ C++.
3:08 you can use:
int* hvalue = new int(5); //save 1 line of code xD
Right, like using a built-in constructor.
Great explanation. But I think we're missing an important difference between stack and heap memory. The size of stack memory to allocate is set at compile time whereas the size of heap memory is may be set in run time. Stack memory is more easy to manage and heap memory is more flexible (and maybe more efficient since actually may allocate just as much memory as you need when actually running your program).
Awesome video😀 understood clearly... Kudos❤
You are just awesome brother..!
Maybe you can cover rvalue/lvalue topic it is pretty confusing or move semantics.
@@Franckbery IS that all though? I always though there were like exceptions to that simple explanation.
Done
Your video is always great. Thank you.
Finally dude , its been some time since your last video on C++
Very Helpful, Thanks!
Great video and happy birthday.
@3:12
It is a worthwhile to explain that
the variable name must be declared differently between variable stored in stack and in heap
@Artem Katerynych
In the example he
used int value;
and int *hvalue;
both exist on the stack
while the value of int *hvalue exist on the heap..
That is from what I understand him saying.
A lot of useful knowledge, thanks.
@4:04
Vector3* hvector = new Vector3();
/*Meaning variable called "hvector" which also an object to the structure called "Vector3" is stored in the stack. "hvector" also creates another
variable of it's type in the heap. So, "hvector" is also a pointer.
@Peterolen
Meaning " *hvector " is not an object of Vector3?
this video was helpful enough im almost willing to overlook Caysh
7:28
Thanks. I had never thought of why the stacks grows down, I just assumed it.
But it makes sense now, that’s clever. Thanks. Subscribed.
Wow, this was incredibly incredibly insightful
@TheCherno is the C++ God! 🐐🙏
very clear explain，thank you
finally! the no-bullshit explatation! 🙏