More videos like this, please. I'd like to learn C++ but all these libraries and concepts required to understand how to use it properly are doing my head in. This video really helps clear things up.

I learned more in this 16 minute and 24 second video than I did in an entire month of drag and drop “programming” that they tried to teach in school. Thanks for making these videos and explaining everything in a way that’s easy to understand.

As someone who had modern C++ drilled into him by a person many years his junior, I appreciate this series for giving me the mirror opposite experience 😆 One very small nitpick, though: if you look at vector's implementation of push_back with an r-value reference, it actually just calls emplace_back using move semantics. I've found it a good habit to explicitly call emplace_back when your intention is to move an r-value reference into a vector!

Hi Dave, as someone with far too many years of embedded C experience, but only a couple of years of self taught C++ I'm still sort of in the wrapped C category. Though I do like and use Vectors wherever possible. If you are ever stuck for video ideas, then a C to modern C++ conversion course would be fantastic. Thank you for the constant stream of interesting and high quality videos.

Sir, you should now really start considering teaching here on KZfaq. The explanations are one of the best ones we can get out there and especially when it comes from someone who has decades of experience in it. Full scale courses coming from you would definitely help us learn in the best way possible and will also make people fall in love with programming.

That is such a great and straightforward example of the use for unique_ptr. Your epic mastery and years of experience shine through in how clean and clear everything is.

I always listen to your presentations, even if I dont have a specific need for the tech you are talking about, and I have never felt a minute was wasted. Thanks for sharing Dave.

std::vector.shrink_to_fit() is also one of the most underrated functions that exists if you know you are not going to expand it at once, or for not a long time.

Excellent working example. Your coding style is extremely efficient and easily understood.

Excellent video, Dave! I'm retired now, but I had been programming in C++ since 1991. The STL is a wonderful thing indeed! Thanks for your channel!

Thanks for the vid Dave, I just came across your channel and I notice this sort of stuff is a relatively new type of content for you, and I subbed and look forward to seeing more modern C++ features demonstrated!

I think this video has very good intentions, but it has some issues that I would like to point out: 7:45 Avoid using plain enums in new code. Prefer enum class which declare separate types instead of declaring the equivalent of global variables of type int. With regular enums ACE == DIAMONDS produces true whereas with enum class Rank::ACE == Suit::DIAMONDS is a compiler error. (see C++ Core Guideline - Enum.3 Prefer class enums over “plain” enums) 9:01 Although this example tries to illustrate the use of unique_ptr, this is a perfect example of when not to use it. Remember, a vector already puts it's storage in the heap, and already manages it's memory allocations and deallocations automatically. Aditionally, Card objects in this example are really small, so you really are better off passing them by value than by pointer anyway (easier to code, and better performance). But that misses the point of the example. I'm guessing that the idea is to imagine that Card objects are expensive to copy around. I just wanted to mention this, for anyone interested in applying this in real-world programs. 9:18 This is right, but the vector will call the destructor of the elements in a loop. For unique_ptrs this is really slow because you're deallocating a bunch of objects one by one. For Card objects the destructor actually does nothing and the compiler optimizes this loop away. Then the whole memory of the underlying array is deallocated in one go (in both cases). 9:44 There is no need to specify upfront the size, but in most cases you either know the size, or a decent estimate, which is good enough (in this case we know the exact size: 13*4). This is good to avoid "distributed fat". You can get a better explanation in this talk that you can find here in KZfaq: `CppCon 2014: Chandler Carruth "Efficiency with Algorithms, Performance with Data Structures"` around 21:28 10:53 You actually CAN have multiple pointer references to whatever a unique_ptr points to. They are just non-owning references. You do this by getting a raw pointer from the unique_ptr using the get() method. Contray to popular belief, raw pointers are actually fine in modern C++, you just have to avoid using them for memory management. You accomplish this by never calling new and delete manually. Other than that, raw pointers are just fine. (see C++ Core Guideline - R.3: A raw pointer (a T*) is non-owning). 11:43 You might want to make the random device and the random engine objects static. Just to avoid constructing them every time that you call shuffledeck. Construction of these objects is fairly expensive, and just adding static does the trick for simple cases. For a thorough explanation, see the talk `CppCon 2016: Walter E. Brown “What C++ Programmers Need to Know about Header ＜random＞"` 12:55 std::move is pretty counter-intuitive and actually just does a type-cast. It might or might not trigger a move by changing the type, depending on the context where you call it. I think in this case we're not changing the type at all (the call to std::move does nothing, and can be removed), but the move still happens. Additionally, since the move happens, the unique_ptr in the vector is left in a moved-from state. But it is fine in the end though, because he does the pop_back right away, removing the moved-from object. The explanation saying that it would be fine even if left in the vector is wrong. It is undefined behavior (UB) to do anything other than detroying an object in a moved-from state. So if it was left in the vector, a sub-sequent drawCard() could draw that same card and then any operation on that drawn card would be UB (including the possibility of corrupting memory, though most likely you'll just segfault). More explanation in the C++ Core Guideline - ES.56: Write std::move() only when you need to explicitly move an object to another scope. For a thorough explanation, this is the talk: `Back to Basics: Move Semantics - David Olsen - CppCon 2020`. 14:01 You're indeed never duplicating cards. But even if you use value semantics (aka. a vector instead of a vector ), which would involve copying card objects, you are still avoiding all of the pitfalls of manual memory management.

Amazing video. At my university, so far we've been basically taught "C with Classes" as you mentioned in the video. I have had some assignments involving Vectors but as I've already used ArrayLists in Java so it's nothing new to me. I have came across the new pointer types in modern C++ and read a bit on them, but this video made them very easy to understand and I really appreciate it!

I'd really like to see a follow-up to this that would show how a "C with Classes" style would write thw same program. I'm guessing it would simply replace the vector with an array, and the unique pointers with regular pointers, but it would be nice to go over exactly where the memory and aafety issues can arise. Also, I really hope you do a Rust video. The safety and performance of Rust is amazing, but it's actually the developer ergonomics and the ease in importing and project orchestration that makes me dread touching the C++ project I have to maintain.

Having followed your channel for some time and enjoyed it, I am so happy to see this kind of information presented in a simple, understandable and usefull way. The information you are giving, may very well be under utilized. Thank you so much Regarding the "modern" part, a fun fact is that I have been using vector (from the original STL) since 1994 (almost 30 years ago) and std::vector since C++98, smart pointers (std::auto_ptr and Boost smart pointer) since late 1990's. Move semantics and std::unique_ptr (from C++11 - 12 years ago) was a huge improvement. I am so impressed that Bjarne Stroustrup's RAII from the very early days of "C with classes" brilliantly holds up so well 40 years later. For almost 25 years I have promoting that "writing new/delete in C++ application code is almost always suboptimal and error prone".

More videos like this please Dave, you are a great teacher and I always learn something from you. Thank you for all your hard work. John, Ireland 🇮🇪

You are an excellent teacher Dave.

You can also put "using" at the top of any scope, for instance a single function in which you expect to type std:: a lot. Sort of a compromise between convenience and risk reduction.

Hey Dave, these C++/C insights are friggin amazing. Thank you

Thanks for the super explanation. I hope this playlist gets more videos. It is very exciting to learn from someone who has been involved with the technology for so many years.

This is why I loved the programming competitions in school. You get no packages, you get no web pages to look up, you must know the language and what it offers, like std. Always loved watching the java guys tell me c++ is bad for string processing problems while mine worked and they never even reached submitting an answer. If you use your tool better, you'll still get better results, regardless of tool.

Since the video is about "modern" C++, a couple of code-review pointers.. 1) Line 9-15: You should use "enum class" instead of "enum". The former (available from C++11) will avoid name-collisions. 2) Line 86: You don't need to insert a space between two ">"s like "> >". You can just write ">>" since C++11.

Dave, I love your videos man. You’ve got a real talent for explaining this kind of stuff in a way that’s easy/clear to understand.

I’m enjoying the elementary code snippets. It helps as I start learning. I’m an old FORTRAN guy so it’s takes me a while to get going in the right direction. Thanks.

Very interesting. I am a very old programmer. But not on UNIX or Windows, but "legacy" IBM z series hardware, back to S/370 days. I was introduced to C/C++ back in K&R times, on Windows 95. Nice to see the C/C++ language continuing to advance.

Seriously thanks for this video. As a novice c++ dev with about 6 months worth of experience, its great to have my eyes opened to what a very experience dev has to say. I'd love to see more videos like this. Thanks :)

Just as a note for those that use the Qt framework.... you can use the QScopedPointer and QSharedPointer classes instead of the std unique and shared points repsectively. Also Qt provides the QVector class to handle vector operations.

So many years ago, because I was a bad c++ programmer, I wrote an app to find the match between my new and delete and my new[] and delete []. If I could not find the corresponding deletes, then I had a leak. If I used the memory after a delete then I had an access violation. My coding is not very sophisticated so my errors may not be very sophisticated, But the utility I wrote still works pretty good for me.

Thanks Dave, I'm pretty bad with c++, C fundamentals I'm not bad but I end up reinventing the wheel, I sort of have to how I learn and I really only make .dlls to interact with an API [dj program] The only stuff that "sticks" is the stuff I use. I'm internet taught, so I've gaps, and I really don't know best practice, it works or it doesn't. vectors I'm down with, you're right about the name [writing xml from raw data made me face the fear, the API uses c_strings for the speed] mt19937, I've used that before too. I recently made a d3d11 thing and my API tutors recommended CComPtr, every d3d11 tutorial uses ComPtr, confusing and frustrating for somebody who barely uses normal pointers, But I got there in the end [rendered cat.png with alpha] Content like this I really enjoy thanks [that said I don't think you've made a bad video yet]

I've been really wanting to get back into C++. I diverted to C# back in a time where conventional wisdom told you to actually avoid the C++ standard libraries (a long, *long* time ago). But much like how C# isn't anything like it was when I first started learning it (remember when they championed verbosity?) c++ feels like a completely different beast now.

Great video, clear explanations. I need more modern C++ examples like that!

The at() function of vector has two nice features: first it does bounds checking: it throws an exception if the index is out of bounds. Second, it is const. So it can be called on a const vector, unlike the [] indexing operator. I think the best usecase of custom deleters on unique_ptr and shared_ptr is that it can be used for any thing that needs a close() style function. So you could make a unique_ptr to a file, where the custom deleter closes the file. Now it is impossible to forget closing the file: the deleter will do it automatically when the unique_ptr runs out of scope. This can also be done for database connections and anything that needs some kind of close function. It's a bit like the try with resources thingy of java, only done right.

I took a long journey away from C++ and haven't looked back, but this gets me interested in poking around once again. Thanks Dave.

Dave, can you do a video on exactly how Compatibility Mode works in Windows? I think that'd be fascinating to a lot of people.

The blurred background is amazing. Makes me want to stay glued to the video.

Thank you so much for the effort 👍, you already made my day . We are looking forward for more into this valuable in-depth technical stuff.

Even though this is C++ 11, released 2011, what makes this possible was from the beginning in the C++ language: constructors and destructors tied to scope, simulating value semantics. So the std lib gives modernized concepts building on that. One crucial thing for the language was move semantics also added with c++ 11 to conveniently handle moving objects between scopes, for objects that need to be unique, not copyable.

Great to see the return of the Friendly Giant. I missed him.

I definitely would have more videos about c++ intermediate topics, absolutely love the content! Thanks for making this

The Friendly Giant!!! You have just become my favorite C++ person. , Wow! great video learning a lot.

Great video. I'm often surprised by the amount of coders who seem to be unaware that modern idiomatic C++ avoids many of the pitfalls of C. I've been using C++ both professionally and in personal projects now for years -- with RAII, the standard library, and move semantics, I find I almost never have to directly use dynamic memory, new() or malloc() or worry about memory leaks. The few times I ever need dynamic memory (e.g. for dynamic/virtual dispatch), std::shared_ptr or std::unique_ptr suffice, and if I need a chunk of memory (e.g. to pass into a native win32 function), a std::vector suffices.

I think one of the most important features from the C++11 was the move operation.

Haven’t touched C/C++ in 25 years or so…still, when I see your content I somehow get itchy fingers to write code again; keep up the great content :)

I've been a fan of the Standard Template Library since it's early days at HP.

Actually c++ std library has an std::array container which encapsulates a statically sized array, where std::vector container encapsulates a dynamically size array, also the capacity of the std:: vector with 1.5x the size of the vector length, when adding data to a std::vector and reaching the max size std vector reallocates the vector with 1.5x the size needed, for speed improvements, because heap allocations takes time(more than a simple copy of data) Besides unique pointers there is shared pointers(shared_ptr), shared pointers have the option to retain the same data through multiple objects of shared_ptr, to keep track of the data they use a reference counter, where it is increased when the object is shared with another shared_ptr object, and decreased when the shared_ptr object is deleted. Only when the reference counter reaches 0(the last shared_ptr was deleted) it will actually delete the data. Modern C++ has a lot of containers that help code C++ much easier and managed, the threading library was build preaty easy since c++ 11

I love the STL library. I tell people there is two era's in C++ Pre-STL and Post-STL. They are different. I have architected 3 major systems in the Mechanical CAD area. I started a big project using STL with shared pointers in ~2005. It was pre-C++ shared_ptr, so I developed my own. It basically solved all of the memory problems. I never switched to the std::shared_ptr because I liked my shared pointers better. They use an embedded count, uses one allocation instead of two. Also changing over a million lines of code to std::shared_ptr would be a pain. -Kurt

Great video, thank you very much. You have the best explanations of code i've ever seen on the web.

Who doesn't want to see more of Dave teaching code.???? I'm a long time programmer of various languages, and I'd still go through the entire catalogue if Dave were to release a C++ from beginner to winner program!

You need to be careful with Vector like containers. If you are going to add a lot of objects, you need to make sure that you allocate a size big enough to avoid growing the memory internally. The memory internally is usually implemented with arrays. When it needs to grow, it allocates a new array according to some internal metric. Then it copies the contents of the old array to the new array. This isn't usually a problem if you're adding 52 cards, but if you're adding a 1,000,000+ objects, you can take a performance hit.

That's a really helpful video, I absolutely love the description of "C with Classes", this perfectly describes the pitfall I have fallen into myself!

Nice walkthrough Dave. Vector is a very powerful structure. I recently created a C implementation for a hobby project I'm working on for my Amiga 500, used LLVM on my Mac to test it thoroughly for RAM safety issues first. I wasn't aware of the unique_ptr capability as I never really made the leap fully into C++, I was definitely the C+Classes kind of dev. 👍

Hi Dave, as you asked to write a comment for a suggestion, my biggest issue in using C++ is that there are many many ways of doing things, and it is not very clear, even when looking for it, which options are obsolete or anti patterns, and which are good. This video goes a long way of addressing this issue for memory management, although there are of course parts missing to keep it from getting too long. But more videos such as this which tell us, topic by topic, how to do it in modern C++ and what to avoid would be fantastic!

Very good synopsis… I still get hit in my childhood feels with the friendly giant ending. The CBC overlay is also a nice touch. :)

love the coding content. keep em coming

Only just trying to get my head round C++ and your videos are great at trying to understand it all

std::move() is a whole can of worms 😄 What it actually does is it returns an r-value reference to whatever you pass into it (the moved-from object), which in turn calls the move assignment operator (or move constructor) of the object being assigned to (the moved-to object). A lot of people use it wrong and think it deletes or deconstructs the moved-from object, but as you correctly pointed out this is not the case. You'll still have a leftover moved-from object, in some state, that you have to deal with. In fact just passing an object to std::move() and discarding the return value does exactly... nothing.

Good info for sure. There is no doubt that C++ code allows for better memory management over C and these tools expand on that. Still, the programmer should be taking steps to keep things tidy. I'm a hobbyist and usually find myself debugging things where I am rotating or swapping elements in an array.

Nice little review. Haven't really touched C/C++ in quite a number of years.

Dave, This is an exciting video. I see C++ in an entirely new light. Thank you so much!!

Dave, I was using std::unique_ptr 15 years ago - it was very helpful. Rust is only the second high level language allowed in the Linux kernel in its 30 years. Microsoft has begun replacing parts of the Windows kernel with Rust code. Rust is the first of a new class of code languages - please dig deeper to understand why. C++ coders can learn Rust easily.

I've found that a lot of the older languages tend to have libraries like this that extend their functionality, so they have parity with more modern languages. It's a shame that they are often overlooked. I think that a lot of coders should at least spend a little bit of time with C or C++, even if it's just a few weeks, you'll learn a lot.

Thank you. I like to watch your videos because you really know about the subjects you are talking to. I can here fortify my knowledge.

Excellent video, good distillation. I have been programming quite a bit of C at work which has made me curious about C++ again. I haven’t programmed C++ since college but I have heard that C++ has many more features than it used to. Unique pointers are def something I was interested in

Smart pointers came out in 2011. Vectors have been around longer (1998?). Both really great features, but there are so many amazing changes since then!

A couple of things which are mentioned in the Core Guidelines concerning enums: 1. Use enum classes, not enums. Enum classes have the advantage of being type safe, and are not implicitly comparable/convertible ints or other enums. This can help a great deal to alleviate stupid but hard to find bugs. 2. This is more of a style preference thing, but still. Don't use all caps for enum elements. Partly to differentiate them from macros, and partly because it's annoying to read and write.

Listening to you is like reading a condensed well written no fluff book, without the reading. Well done

Very good video! I have been using C for some small projects recently but now I see what modern C++ can do I'm quite surprised

I haven't touched c++ yet I was thinking of trying it after learning c, good tutorial. Vector is really an intimidating name for a dynamic array, I think that does names are really threatening for beginners in c++.

Dave, I really love your videos - the only thing that makes me sad to a certain extent is the vector - it is a sure fire way to spend most of your CPU time dealing with cache misses. I am sure you are aware that it is a pointer to a list of pointers. I might be old though. Maybe this does not matter for most programmers today. I deal with this kind of stuff all the time when working with high performance code. For what it is worth, I understand your goal - memory problems are an issue for sure.

Dave I don't know if you'll see this but my Friend I wanted to thank you. First you have an amazing audience base. This comment is outside of the scope of the video, sorry about that. But still it wasn't till I discovered your channel a while back and found you were autistic that It motivated me enough to start my own channel. I scared but a few of your viewers supported me and one was even kind enough to give me my first subscriber to help push me forward in my channel creation. I wouldn't of had a channel if it wasn't for your supportive audience. And I got no one else other than you as well for being an inspiration. Now unfortunately my channel has been sputtering and has really gain much traction but that's my fault. I had no idea how youtube worked and never created a video in my life. But I'm planning an overhaul to get things going again. Thank you so much for such an amazing channel. For the inspiration and thank you to anyone reading this for being supportive to a man who used to be scared of his own shadow and thanks to you found his voice. Sorry for the long comment but I just felt a need to send a big thank you to everyone. 👍

Nice to see a good practise for C++ introduced early in the learning process. I spent years fighting in the way described in the introduction. I give c++ another go.

I know this stuff but still throughly enjoyed you stepping through it. There was a time before I became comfortable with STL where I programmed pretty much how you said. I disagree with that the vector class should be called the array class. STL has an array class that functions like a version of the C array but with useful helpers. I’d find it confusing at least if these got swapped around. :)

Finally, someone on the entire Internet who actually knows about the STL. I was getting more and more annoyed by the "Rust cultists" lately, you probably know what I'm talking about. Thanks for the video!

I'm back to C++ after 20 years thanks to Dave - in between, I visited the Python, Java, Rust, Julia, Typescript, Haskell and Lisp lands. C++ is like old wine - the older the better. Excited about C++ and WASM (another area where Rust has mindshare), Mojo and Zig.

Nice work Dave. Much appreciate this kind of content.

The point is you are not shooting yourself in the foot, because you know better. Many people do not. That is why Rust exists. Foot shooting should be an unsafe operation.

I use unique_ptr in my current project but sometimes I still encountered some issues with dangling references that Rust borrow checker could've catched at compile time. So I really have a hope to write my next project in Rust.

Thank you for making this simpler to understand

Thank you! As an experianced dev, this video was the exact level I wanted; You don't over explain and move fast

Hi Dave! Oh, and first :)

I'm pretty lame on C++ but as i understand unique_ptr and shared_ptr have additonal cost and it is not "zeroed" by compiler or i'm wrong ? I'm also lame to Rust, but as i understand protections in Rust are forced in compile time so have no runtime cost also this philosophy allows Rust compiler to futher optimize than is allowed in C++ or C. Hype is really strong but i'm almost sure you underestimate Rust because even if i'm wrong on pointers and memory protection Rust also brings very powerfull type system wich can let you protect future programers from generating or even represting incorrect states also in compile time...

I loved this explanation and tutorial; please continue with this series!

You skipped over the hand value method but here we are actually doing something interesting: borrowing cards for the hand

Rust: it protects you from yourself. C++: you must protect from the language itself. The fact that they designed a whole library to get around even the most basic issues of memory management, already speaks a lot. Listen, C++ has been my first language, and I was deeply in love with it. I mastered many advanced books from head to tail. I delved into the bottomless pits of template metaprogramming, hardcore operator overloading, and the likes. C++ gives you great power, but :) If you need execution speed, I think C++ is still the best out there. But most of the time you need DEVELOPMENT speed, and also out-of-the-box reliability and readability. And C++ can't compete there. I had to admit it to myself, a C++ fanboy, more than 20 years ago...

...new? aren't smart pointers a decade old?

I enjoy your recent videos such as this one, which are of interest to people learning embedded programming.

I wish I could think that unwavering and plow through programming logic in calm order that fast. Sharp as a knife. As if I was talking casually on the way to the bus. Now I understand what Bill meant with assigning to projects the right 10 or fewer people.

If you must use C++, do use these features, for sure. However, do also be aware that C++ is an unsafe language since it does not allow the enforcement of these features at compile time level. Sure, your code might be great but your compiled dlls might not. This means you can only be 90% sure there will be no memory leaks - using Rust OTOH, you can be 99% sure.

Dave, I get the feeling you think rust is solving a problem that doesn't exist or that can be solved in other languages like c++ by just "using the right tools", but I promise thinking like that is missing the point of rust. If you have the time, I would really recommend really learning it, reading "the rust book" and following along with it, writing and building the examples, its not that long even. Part of the problem is if you write rust code like a c++ developer the language is awful, you have to learn not just the language but the idiomatic ways of doing things to really start to see the benefits of rust. Love the vids

Really appreciate this one. I'd been interested in learning a lower level language recently just out of personal curiosity and debated whether to invest my time in Rust or C++. It's cool to hear your perspective that C++ already has robust ways of handling memory safety. Feels like that's a point that doesn't get said very often.

Thanks for helpful video. Please do more of this series.

I might be biased but this just looks like janky, Rust like behavior in a still bloated and unsafe language... Everything registers like "oh so how Rust does it but worse" to me.

If you want to write safe modern code, you should not be doing it in c++. No matter how many optional safety features the committee adds, they will never be able to reduce the chance of footgunning anywhere even near the level of what actually modern languages offer. (cough, rust, cough)

Will mention that I had problems with this due to an error in random_device in MinGW always generating the same sequence of numbers. Downloaded and installed Clang and it worked great. The MinGW bug was fortunate because it made me really study the code and refresh my old knowledge of C++.

Congrats , this blows the competition away …, most of the tutorials don’t give you those nuances, perspectives molded by decades of experience

idk why people hype up rust so much they probably dont know any c++

"modern C++ stl has essentially the same protections (as Rust)" - sorry, but that's complete BS. Lemme know when your compiler warns about invalidating references due to modifying a container inside a loop. Or what about a dangling reference, you take a reference to something in the container and then it gets resized. Silent, critical failures.

Please more programming videos including stories about programming from you carrier - serious or funny ones! Thanks for the content! It's great!

Dave thank you so much. You said "vector is just a dynamic array". I have just spent the better half of a course trying to get my head around it and researching it, but no one put it in those words that just dispelled any lingering doubt of me not understanding exactly what I'm doing. Someone also described it as a drawer with folders, in that if you want to add something you add it at the start of the array and shove the rest of the files one step back in memory so to speak, thus side-stepping the need to copy the entire drawer into another location in memory before adding the new entry to it. Someone please correct my understanding but this is as best as I've understood it so far.

Great example and explanation. Thank you.