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 UA-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
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 ?
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!
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!
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.
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 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!
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
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!😃
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 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.
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.
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.
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...
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
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 !
The CPU has several levels of caches that are much faster than ram on the motherboard, but the kind of memory is more expensive and has to fit in the CPU, so there is a lot less of it. When data is used accessed it will load the whole area of memory to the cache. If the next data it needs is in the same area it will already be loaded. If not you have a cache miss, so it has to load more from ram to cache, and that's slow. Basically when you have a cache miss the CPU has to sit on idle while waiting for the data -- if it was already in the cache it could just keeps going. It could make things 50 or 100 times slower if you have constant misses versus very few (if there is much data some will happen since only so much is moved at once). This is an advantage of arrays over linked lists -- linked lists cause lots of misses, which makes them much slower than arrays even at things they're better at in theory. That's simplified a bit, since different level of cache do have different speeds too, but that should give you the general idea.
@@BlackJar72 Thank you so much!!! Throughout the whole video I was wondering what "cache miss" means, I was so happy to find your explanation (which is very easy to understand, so kudos!)
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, 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.
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 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! :)
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!
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.
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 :-)
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
"Stored in the caysh"
caysh money dawg
I understood cage first, then caysh, then i understood that he actually means cache
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 UA-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?
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
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
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 ?
This stuff is all great man. All of your C++ videos have been amazing so far.
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!
I think this is my favorite video so far. I always wondered about the stack and heap differences. This is such a good explanation!
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!
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.
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 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!
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 video helped me a ton with interview questions, thank's so much!
Very clear and easily accessible explanation, even the explaining with asssembler was just really supporting understanding.
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!😃
I learn so much over this channel thank you for the hard work!
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
wow, this video is wonderful! It answers a lot of my questions. Thank you Cherno!
You are awesome Cherno! Thanks for your clear explanations!
Thank you so much for your serie Cherno, I always learn alot watching you
Happy holidays to you and your friends/family :)
Thank you for this really great content, Cherno!
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!
Excellent refresher for me. Subscribed.
Happy Birthday & Thank you very much for your great content! :)
Amazing explanation! Thank you!!
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.
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.
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.
Amazing video! Thanks. I just subbed.
THANK YOU SOOO MUCH MAN. VERY HELPFUL VIDEO, LOVED IT
Very nice and informative, I am kinda addicted to your videos gj.
Best content i found....Crazy, how it is simple and detailed 🔥.. Thank you
You're the best man excellent explanation, thank you
Thank you so much for this content. It's been very useful for me.
dude, you're awesome! I've learned it like a piece of cake!
Next level videos. Thank you!
This is the best explanation video about Stack vs Heap I ever seen, Thanks man.
Its was super useful video. Thanks and Gratitude!!
Many thanks for your effort and your very clear explanantions.
You are a king. Excellent explanation, 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...
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
your videos have been very helpful to me. I hope things are going good for you Cherno :-)
Awesome video😀 understood clearly... Kudos❤
Just subscribed. Enjoyed the content. 😇
Wow, this was incredibly incredibly insightful
I just nailed an interview question because of this and other videos. Thanks so much.
I love you! YOU ARE SUPER HELPFUL !!!!!!!! KEEP THIS PASSION ON MAKING VIDEO. YOU ARE TALENTED
Clear, ,fluent and to the point explanation, thanks.
Brilliant explanation thank you so much and please continue
Thanks a lot man your videos are so helpful , keep going 💙💙
amazing, explained really well and in a clean way
Very well explained, very good examples!
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?
Thanks for explaining this sooooo clearly and in an easy way!!!!! very useful!
Your video is always great. Thank you.
A trendy looking programmer that makes good quality programming tutorials on UA-cam that doesn't use a mac?
Respect.
I enjoyed the video. Thank you!
Very Helpful, Thanks!
I'm not familiar with the concept of "CPU cache misses".
The CPU has several levels of caches that are much faster than ram on the motherboard, but the kind of memory is more expensive and has to fit in the CPU, so there is a lot less of it. When data is used accessed it will load the whole area of memory to the cache. If the next data it needs is in the same area it will already be loaded. If not you have a cache miss, so it has to load more from ram to cache, and that's slow. Basically when you have a cache miss the CPU has to sit on idle while waiting for the data -- if it was already in the cache it could just keeps going. It could make things 50 or 100 times slower if you have constant misses versus very few (if there is much data some will happen since only so much is moved at once). This is an advantage of arrays over linked lists -- linked lists cause lots of misses, which makes them much slower than arrays even at things they're better at in theory. That's simplified a bit, since different level of cache do have different speeds too, but that should give you the general idea.
@@BlackJar72 Thank you so much!!! Throughout the whole video I was wondering what "cache miss" means, I was so happy to find your explanation (which is very easy to understand, so kudos!)
@@BlackJar72 May I ask where you learn about this. University? A book?
@@mryup6100 experience
@@PatrickRobinsonZA
Experience out ranks everything
Sick bro
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?
Your a very clever guy. I find your videos extremely helpful
Great video and happy birthday.
A lot of useful knowledge, thanks.
thanks dude, good explanation
very clear explain，thank you
You are just awesome brother..!
Awesome video !!!
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.
Wow! Thanks for this video!
Great video!
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.
Wow. This guy is next level and then some. 🔥
words cant describe this video thanks for helping
I just enjoy u talking, very easy to absorb
Finally dude , its been some time since your last video on C++
Thank you man! :)
still such an amazing and practical video now it's 2021.
Very didactic!! Greetings from Brazil!
Great teacher!
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! :)
Very nice. Thanks.
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.
This is sooo awesome!!!!
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
This was a very clear video which made a lot of sense.
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!
Awesome video! I thought it was going to be a lot more complicated than this. I'm glad it's not :)
this is totally amazing
Thank you so much!!!
This was super interesting. However, thanks to you, I have spent hours looking at assembly code trying to figure out what it is doing.
Thank you!