you will never ask about pointers again after watching this video

Рік тому

One of the hardest things for new programmers to learn is pointers. Whether its single use pointers, pointers to other pointers, pointers to structures, something about the concept drives new programmers crazy. The C programming languages is recognized as one of the most difficult programming languages to learn. The reason for this is the limitless power you have over memory management, which comes from pointers.
In this video, I show you what a pointer is, as it applies to low level memory access. Also, we talk about pointer syntax in C and how you can better understand the pointer syntax by converting it to English. And we wrap the video up by asking "why do we care?".
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КОМЕНТАРІ: 1 600

@LowLevelLearning 7 місяців тому

come learn to code in C @ lowlevel.academy 😎

@VeritasEtAequitas Місяць тому

It's easy. Just add or remove asterisks or ampersands until it works.

@rohanjoshi8785 Рік тому

Working with pointers is easy af... Just try different permutation and combinations of & and * until code works like u wanted it to work... Don't complicate easy things.. xD 😁😁

@tenseikenzx-3559 Рік тому

Next thing you know it, you created a buffer overflow attack

@dakata2416 Рік тому

@@tenseikenzx-3559 And that's why we use Rust

@TyconXstar Рік тому

This is wrong in so many levels 😂

@williamdrum9899 Рік тому

Me after 20 minutes of compile time errors: __asm__ { MOV DWORD PTR [0xDEADBEEF],%EAX }

@anon1963 Рік тому

@@dakata2416 no. that's why we use unique_ptr or shared_ptr.

@Mutual_Information Рік тому

C++ was the first language I learned.. and I only spent a short time with it. But one thing that made all the difference was having a mental model of computer's memory with addresses and values. Before I knew to do that, C++ was incredibly frustrating. This video is smart to lead with that lesson.

@imt3206 Рік тому

Any resources on learning how computers handle memory?

@iloveblender8999 Рік тому

@@imt3206 If you want to learn the basics, you could learn about Stacks first: en.wikipedia.org/wiki/Stack_(abstract_data_type) All programs use one or multiple stacks. Functions are called using the stack. While the actual implementation (if you want to write an operating system) is complicated, it will still be usefull to learn this stack model, if you want to get started with coding.

@thebirdhasbeencharged Рік тому

Same, I taught myself C++ well over a decade ago at the wee age of 12 and it took me near 2 years to get pointers. I remember what finally made it click was an analogy comparing it to actual mail addresses, will never forget that enlightening moment.

@antoniusdaivap7759 Рік тому

@@imt3206 in my case, learning how computers handle memory is automatic with learning pointers and data structures like array, stack, qeue, linked list. especially linked list, that shit opened my eyes how linked list is so much superior than array in most cases

@TheMovieCriticVoice Рік тому

ukposts.info2YCtH5_56po?feature=share

@fang8244 Рік тому

One important clarification. The asterisk(*) is an attribute of the variable not the type which your explanation seems to suggest. This distinction is important because if you consider the following line: int* x, y; x is a pointer to an int while y is just an int. If you wanted both to be pointers you would need to write something like: int *x, *y;

@FriedMonkey362 Рік тому

So i should do int **pX; instead of int** pX; as a good habbit

@jeremiahbenjamin5776 Рік тому

@@FriedMonkey362 yes

@fang8244 Рік тому

@@FriedMonkey362 It's up to you. That is how I prefer it as I feel it more accurately reflects the syntax, but Strourstrup (founder of C++) actually prefers it *int* pX;*. There is not "right" way per say, so do what you think makes sense : )

@xouxoful Рік тому

That makes sense : *pX (value pointed by pX) is, indeed, an int.

@kiryls1207 Рік тому

but int * x, y; is just a syntactic sugar to condense on one line this: int * x; int y; during declaration phase the * operator is treated like the type of memory you'll allocate, otherwise it becomes a unary operator to dereference pointers. so when you declare variables it actually makes sense to read "int * x" as "x is a pointer to int" and otherwise, seeing "*x = y" as "assign y to the address pointed by x"

@kingofthecrows8802 Рік тому

I'm a senior majoring in Computer Science at college. If you're a young person whose looking to learn about programming and computers, keep watching this guy's stuff! All complex systems can be broken down to simpler parts. That's what this channel does very well when explaining complex concepts like pointers. This is the first video I've seen but I'm definitely subbing cuz this guy not only knows his stuff but more than I do! My college experience was incredibly lacking in low level courses, which I imagine will be the case at many other universities in the coming future. High-level problem solving has it's place, but low-level is important because a house won't last without a proper foundation. The foundations of computer science are the most important area to master, arguably more important than programming itself. Don't be a cog; be the future.

@coolperson4582 6 місяців тому

What programming languages were pushed at your college? My college is pushing C++ right out of the gate and forces us to learn Assembly as well. Is your college similar?

@pewpewyadead 3 місяці тому

love this

@Matt-ir1ky 2 місяці тому

@@coolperson4582 What college? You're lucky, enjoy!

@4F6D Місяць тому

@@coolperson4582 You are so lucky, my university enforces java and eclipse. It feels like oracle is lobbying there.

@bojan6368 Місяць тому

@@coolperson4582assembly in 2024?

@Ogrodnik95 Рік тому

Understanding references, pointers, smart pointers and memory is gamechanger and is crucial thing to know. Dont give up trying to understand, it is well worth it and with bit of practice becomes normal to read and understand. I regret giving up programming because of this at school, it would have boosted my career as software engineer forward by years had i put more time into it.

@abdiasisibrahim5903 Рік тому

But can’t find practice problems online. So far being working with this company for about 7 months and everywhere in the codebase we use pointers and I just get more confused especially when a pointer or reference is passed to a method and returned from a method

@Ogrodnik95 Рік тому

@@abdiasisibrahim5903 best practice i got was when i tried to make my own simple tile based farming game, so i suggest trying to create something of your own, and when problems arise you need to understand and solve them. I didnt ever finish it, so i cant really show how code looks like, but one of many problems i had was how to grow plants, which I resolved by creating timer, to which I subscribed selected plants and called grow method on them when timer said it is time. Problem also included how to unsubscibe them correctly. Another issue arised when my game grew too much and I had to split it in smaller modules, so eventually I needed to separate drawing routines from game logic. I remember it being tricky, as my game directly extended from engine. I stored tiles and other assets in raw arrays stored at heap, so it also needed some thought to put into. Such practice directly tests your knowledge and teaches you a bit about design patterns and how memory and language works.

@zanityplays Рік тому

Making game trainers is a great way to learn about pointers

@abdiasisibrahim5903 Рік тому

@@zanityplays how do you make game trainer (sorry I’m not a gamer)?

@zanityplays Рік тому

@@abdiasisibrahim5903 you use a memory searching tool such as cheat engine to find interesting in game stuff such as player health, some debuggers also have this functionality. Then use relevant os APIs to retrieve a handle to the process and modify data at the found addresses

@williamdrum9899 Рік тому

Video idea: How malloc() works and how does it know what memory is considered "free to use". I started programming on retro game consoles where you know ahead of time exactly how much RAM you have at your disposal, so allocation functions in general are very "alien" to me.

@gustawbobowski1333 Рік тому

malloc doesn't know. The OS knows.

@williamdrum9899 Рік тому

I figured as much since MS-DOS had a "malloc" feature where you would tell it how much menory you needed and DOS would tell you where it is. But how does the OS know then?

@mihailmojsoski4202 Рік тому

it probably uses mmap or sbrk

@Rodrigo-me6nq Рік тому

@@williamdrum9899 Why wouldn't the os know? That's one of the core functionalities an os provides

@strongserbian1413 Рік тому

@@williamdrum9899 it's still the same on any OS if I'm not mitaken. The OS has a map of available memory blocks allocated to your program (called pages). When you call malloc, which is a system call, the OS finds a contiguous space of memory allocated to your program where the size you asked for would fit. If not enough memory is available in your page, a new page is allocated to your program.

@olteanumihai1245 Рік тому

The best tutorial so far. This is what high lever languages do all the time with "references" which is just a pointer bound to a value but you cant play with the pointer directly only the value he is pointing too.

@Nasengold Рік тому

3 min in and I straight up subscribed. The code translation into english is exactly what makes this so easy to learn. Thanks a lot.

@TDG361 Рік тому

I struggled quit a bit with pointers and references back when I was learning C (my first programming language,) but I did not gave up and eventually managed to understand them. They're so simple, yet so powerful, and open up an almost infinite number of possibilities. Sometimes, I managed to break programs when using pointers, but in general I have no problem using them 😄

@arezki712 Рік тому

I really lost hope to learn the .. i do find mathematics and electronics are more easy 🤦‍♂️🤦‍♂️

@ghost_cipher Рік тому

I don’t fully understand everything, but you make me feel like I will one day…and that’s the most important thing I enjoy the most! It’s all about the journey of learning and not always to the final destination! Thank you for this content!

@slickballer 9 місяців тому

How is it going man?

@HolyRamanRajya Рік тому

Understanding isnt hard, applying it cleanly is. Working by bypassing scope might be faster but the need of keeping track of it is hard lest one gets memory leak. Not to mention in bigger teams having to rely on coworkers to apply it cleanly. It becomes a cascading problem with less avenues to debug such bugs. edit: 1yr on seems my post got some traction, I want to add something. One of many uses and evolution of a Computer is to be a better Calculator. To that end, computers must be able to provide to a user mildly complex logical constructs/objects on which mathematics can be applied and work on them e.g. plus symbol signifying Concatenation of String objects. One should be able to develop some function without having to think of this and that memory allocation. Usage of pointers should only be approached by the top 1 percentile of experienced devs who is probably designing a solution for other devs; or embedded devs having to work with low level resources but won't have a cascading problem.

@mastershooter64 Рік тому

That's why we practice! :D

@_khaine Рік тому

@@chudchadanstud then don't put noobs on your dev team

@puppergump4117 Рік тому

@@_khaine You can put me on your dev team

@_khaine Рік тому

@@chudchadanstud not naive at all

@JBeats1493 10 місяців тому

Exactly, all these videos explain the concept well, but the real problem is when you are coding something and you dont really understand why you need to use a pointer

@nati7728 Рік тому

I’ve been programming for years and I still feel like this video flipped a switch in my brain. Excellent, I’m going to bookmark this

@cindrmon Рік тому

i actually appreciated pointers more when i started to learn golang! it really helps especially when you don't always want to expect a return type when making a function and just modify a value that you pass into

@robertmarder126 Рік тому

Yes, that's called passing by reference, and it's a very useful feature in many languages to save function call overhead and to return multiple results from a function.

@iCybqr Рік тому

Yep! Acknowledging the difference between pass-by-value and pass-by-reference is quite important, and it helps a lot to deeper understand a language.

@iCybqr Рік тому

One decent example can be seen in Visual Basic (just the first one that came to mind), where a methods are assigned a role: either a subroutine (no return value) or a function (has a return value). The function/subroutine parameters can also be prefixed with “ByVal” or “ByRef” depending on what you are going to do with those arguments. It’s quite flexible, but sometimes a bit difficult for some to understand

@gg-gn3re Рік тому

yep, Go is awesome

@iCybqr Рік тому

@@gg-gn3re I wholeheartedly agree :)

@od1367 Рік тому

thank you so much professor, you taught me something in 8 mins!

@LowLevelLearning Рік тому

Happy to help!

@ramakrishna4092 Рік тому

@@LowLevelLearning hi I am seeing your videos from a week I noticed that your explanation made all our ways clear in doubts but I have a question in this pointers topic on embedded c ? The question was why pointers don't use in embedded c Can you pls clarify the following questions with your explanation I had this doubt after watching this pointers topic in your channel...

@audiodiwhy2195 Рік тому

@@ramakrishna4092 Rama, here's an answer to the common question "why we have to use pointers in embedded C". If you use the Pico/RP2040 SDK, you have to use pointers, the functions in the SDK demand that, and I think it'd be almost impossible to code for RP2040 in C/c++ without the SDK. As LLL says at 6:44, I figure the RPi programmers used pointers to get around scoping issues. They had to do it this way, so we do as well.

@mircopaul5259 Рік тому

You think you understand pointers now? Then make sense of this type: int (*(*f())[13])()

@felipeguerrino1341 Рік тому

@@mircopaul5259 wtf is that, lisp?

@tylerrainey223 Рік тому

About to finish my computer science degree, and I never really understood pointers because most modern languages abstract this. It's nice to make a full circle though. Thanks!

@MerrStudio Рік тому

The thing that was the most confusing for me was the syntax and all of it clicked when you simply explained that the star is used for two different things. I just couldn't understand why star next to type is a pointer but star next to variable is a value under the pointer

@antaries778 Рік тому

" star next to type is a pointer but star next to variable is a value under the pointer".. Exactly! I think most tutorials seem to fixate on the memory map element of pointers, which imo isn't that hard to understand. It's the subtly contradictory notation that's that actual source of confusion for most.

@mapu1 Рік тому

Yea, assigning too many uses to the same symbol creates confusion. The concept is easy enough to understand, the grammar is not.

@Bchicken2 Рік тому

Great video, but I think it required more examples of the applications of pointers. Beginners tend to have a small scope of the concept of pointers with a simple explanation. But honestly to me, pointers can never be explained. Its concept and applications can only be truly understood once we've experimented with it hahaha.

@LowLevelLearning Рік тому

Noted!

@fghsgh Рік тому

It's C's equivalent of "no one can explain what a monad is"

@colonthree Рік тому

Exactly. All I need is to see use cases.

@napalm5 Рік тому

Basically if you want to pass a huge struct to a function , instead of copying the whole thing in (ie via the copy by value parameter), pass it in by pointer/reference. Of course if you modify the struct in the function it modifies the original.

@DavidUrulski-wq9de 4 місяці тому

@@napalm5 heh.. that explanation is what I was searching for, thanks

@asadickens9353 Рік тому

I’ve never really used C so i’m more familiar with the newer languages masking this functionality. Listening to this video is really easy to absorb. Honestly if you can show more examples of pointers in a part 2 i think someone could really solidify the knowledge quickly!

@danielacevedo7539 Рік тому

dog

@asadickens9353 Рік тому

@@danielacevedo7539 ong dog fr slay kween

@t0k4m4k7 Рік тому

Great explanation, i think the reason why pointers are so widely misunderstood or hardly understood is the lack of explanation regarding memory layout (which you explained really well) and the not so intuitive syntax

@LowLevelLearning Рік тому

Glad it was helpful!

@yash1152 Рік тому

@@LowLevelLearning umh, not to shoot you down or anything, but if i were being honest, this was like basic stuff. it's fine. the real problem i face is with 2D arrays, and passing them to functions. the one you explained was just plain variables - it was not at all hard for me. even 1d array is managable, but i can never get pointers to work with 2d arrays, and i thought u'd cover those too....

@valizeth4073 Рік тому

@@yash1152 Well arrays decay to pointers but it's only the top declarator that does so. A 2d array hence decays to T(*)[N]

@ShydenPierce Рік тому

this actually answered basically all of my questions regarding pointers and explained them well

@erf456 Рік тому

I first learned about pointers while trying to make Whack-A-Mole with an Arduino. I wanted to pass a “mole” struct into a void function to mutate it, but couldn’t figure out why it wasn’t working… wish I’d seen this video back then; it would’ve saved me several hours of confused googling lol

@tonysofla Рік тому

If you have an array of structs, a pointer would be like passing the number inside the brackets, like array[0] or array[3] etc. As C pre complies everything in to tetris blocks repeated at a fixed interval, as each struck inside the array are 12bytes in size (example), so now you can refer to struct members with and offset of 0 to 11, you just pass base number to the functions, an absolute address in memory that is the base number to each "apartment block" and that is called a pointer.

@petruciucur Місяць тому

Excellent! I looked at a couple of other tutorials, but only this one helped me. Thanks!

@franklinmontez8733 5 місяців тому

you single handedly solved all my confusion. you are a godsend. thank you.

@BogdanSerban Рік тому

I really understood pointers when I got into embedded programming, where you have to access builtin memory address (registers), read their state or write to them. But wait until you get into typecasting pointers, that gets really fun.

@SoulSukkur Рік тому

every variable can be a char array if you're brave enough.

@clementpoon120 Рік тому

@@SoulSukkur you can swap bytes by casting variables into char arrays

@milky3ay566 Рік тому

And also doing dangerous thing like this is allowed in embedded C bare metal. pointing to random memory. uint32_t *random_mem = (uint32_t*)0x200800FF; *random_mem = 0xEF; //cause weird behaviour or hardfault.

@williamchamberlain2263 Рік тому

The int * can be looked at as the type - it's a pointer to an address space sized to fit an int; bear in mind that different machines or different compilers/options can have different size ints, and declaring that size will let the compiler generate binaries allocating the right number of bits of memory.

@SoulSukkur Рік тому

this comment touches on something i REALLY hate about C. as far as I'm concerned, char is a fundamentally different type to an char*. which, it is. they're a different size and everything. so WHY can we write declarations like "char a, *b;" creating two variables of fundamentally different types in the same statement? it's stupid and i hate it.

@williamchamberlain2263 Рік тому

@@SoulSukkur back in the old days people couldn't type very well. And monitors were very low resolution, limiting the number of characters and lines visible. So characters had to be conserved.

@Anon.G Рік тому

@@SoulSukkur nobody is forcing you to write it like that

@U20E0 Рік тому

@@SoulSukkur i just don’t use multiple-declarations, they are already ugly by themselves.

@cipher1167 6 місяців тому

This is a beautiful video my friend! I sorta got the concept, but this! This video helped me COMPREHEND it!

@aleksandarlukic736 Рік тому

Honestly the best video I have ever seen on the pointers. Great work!

@cryptic_daemon_ Рік тому

I found pointers inheretly easy to understand when i was learning them, what can be hard, for me at least, is how to implement them in an effective way. I can understand the difficulty, since it involves computer memory.

@SkyenNovaA Рік тому

I already understand pointers fully, but your explanation is so good / mesmerizing that I watch anyway. Great video.

@LowLevelLearning Рік тому

Awesome, thank you!

@AdrianTregoning Рік тому

I didn't know what a pointer is but this video is so clear it makes perfect sense. I've watched hundreds of videos over the months and yours are some of THE best. Well done, and much appreciated.

@Retrofire-47 10 місяців тому

i have found that sometimes when i am really, *really* struggling to understand a concept it might simply be a product of obsessively trying to understand it, so your looking at like 50 interpretations of what a function is and bombarding your brain with too much information for the actual concept to have any cohesion. i remember reading that the best way to remember something is, well, i am going to inject the first part 1. apply what you learn to something you care about 2. repeat it [use it] 10 times in a row

@rolandinho5279 Рік тому

Single most useful video i have seen all year! Thank you so much for this

@archmagusofevil Рік тому

Thanks for the video. I learned the basics of programming from PLT Scheme and became proficient from Python. I've been trying to learn C and I have a decent understanding of the concepts of pointers and addresses, but was struggling to understand why we need to pass pointers to functions instead of the object itself since that's something Python handles for you in the background. I want to take advantage of the power and speed of C, though, so this is very helpful.

@LowLevelLearning Рік тому

Awesome I’m happy that it helped!

@sekki2554 Рік тому

A small tip: Change the font you're using in your video. I know, might be weird to hear, but the ; symbole looks so weird, it makes the code look more complicated. I understood pointers years ago and when i saw your code, i was legit scared of it and thought, i forgot something important lol Or sometimes it looks like a " i " and i thought: Yo where is "xi" comming from

@yarpen26 29 днів тому

Same here, the semi-colon got me confused, needed to back it up a bit to confirm it was indeed just a semi-colon.

@Andre-zd7nu Рік тому

I love it! Thank you for this explanation, it made everything clear for me

@JoshuaMartinez-ml5hl Рік тому

Thank you for the explanation! Pointers took me about two years to be able to use them, but I legit just never understood why, other than that we could manually delete them as needed. Never understood why my code would work or not work with or without pointers, but understanding the static and dynamic part really helps

@SuperTommox Рік тому

Love this kind of explanation!

@LowLevelLearning Рік тому

Glad it helped!

@firesnake6311 Рік тому

Finally, I get it! Thanks

@dylanr3875 Рік тому

Thank you for the clear and concise explanation!

@EnraiKorvus Рік тому

this video was recommended to me at a perfect time, working on a final project and I'm mad confused about pointers. Thank you

@hansdampf2284 Рік тому

I come from the field of PLC programming. Until recently you could only program most PLCs with either a graphical programming language (good for logic tasks) or in assembler of the PLCs processor. (Good for data tasks). Pointers were really to only way to implement a loop with a pointer iterating over a given field of data. The good thing is pointers and memory handling are really easy in PLCs compared to PCs, so learning pointers there was a good start.

@mage3690 Рік тому

I learned to program PLCs in tech school about 3 years ago. I tell you this RN, my instructor would've thrown me out on my ear if he ever saw a pointer in my code. He nearly did so when I found the JMP command all on my own, especially after I (mis)used it and created an infinite loop. Apparently, not even he used the JMP instruction regularly in some 15 years of PLC coding, so he was in no position or mood to look at my code, see that there was a JMP going up the ladder instead of down, and correct it before problems arose.

@dsdy1205 Рік тому

getting LabView vibes

@mwanikimwaniki6801 Рік тому

@@mage3690 Haha lmao

@dr_jaymz Рік тому

I think the issue has always been squarely down to the way they are used in c. You cannot intuitively infer what a * or & means if they used terms like addressof instead people wouldn't get so confused. But its like that because only a few ascii symbols were available at the time and so that is the way that it is. If you start by programming a simple micro controller using assembly its gets hard quickly, you basically need a higher level language to take care of branching and addressing memory - when you come at it from that angle it makes 100% sense to the point where you almost invent the need yourself - only to find c has your back. If you don't use c at least monthly you forget the syntax and thats when we get into the stabbing * or & in because we know its one of them of some form. Efficient code uses pointers because its much faster to point or reference data than to keep moving it. The downside is that since an address is just a number you can very easily point to memory that isn't what you intended. Even the best programmers can easily get caught by an edge case - so there's a trade off between efficient and safe code - i.e. you can spend 20 instructions checking the bounds and 1 instruction copying data to be safe but thats inefficient, so it depends on what your doing. By far the largest confusion for students are strings, char arrays, pointers to, const char arrays and when and which to use - discussion for another day.

@NotTheHeroStudios Рік тому

This has to be one of the best channels on youtube. I have been fighting this for so god dam long

@ZRyuzaki06 Рік тому

This video literally made me understand at all what pointers are tbh I was having a lot of trouble with them Thank u so much

@SuperROFLWAFL Рік тому

I think what caused the most confusion for me regarding pointers was when using * as the indicator that a variable was a pointer and using the same symbol to de-reference.... I think it would have caused much less confusion if we didn't use the asterisk for both

@yash1152 Рік тому

> _"* is both the pointer declaring and dereference operator.... much less confusion if we didn't use the asterisk for both "_ yeah, i totally agree

@protox4 Рік тому

Change the spacing and it makes more sense. Func(int *pX) { int y = *pX; }

@dadoo6912 Рік тому

@@protox4 no, it doesn't (int *) - type of pointer, that points to integer number * - dereference operator they're absolutely two different things

@ninesquared81 Рік тому

@@dadoo6912 it's to do with the whole idea of "declaration follows use". The asterisk is on the variable name because in some weird way, it acts as the dereferencing operator within the declaration. Something like `int *pX` really means (in terms of the declaration semantics) "`pX` is something that can be dereferenced (i.e. a pointer) and when you dereference it, you get an `int`." Similarly, `double a[N]` reads "`a` is somthing that can be indexed (an array), where the maximum valid index is `N` (you can only access up to address `N-1`, mind), and when you do so, you get a double." Another example: `void *pointers[5]`: "`pointers` can be indexed up to `5`, and doing so returns something that when dereferenced gives you `void` (you can't _actually_ dereference a void pointer at runtime, but if you _could,_ you'd supposedly get `void`)." Also, `char (*array)[42]` reads "`array` can be dereferenced, which gives you something that can be indexed to give char (max index 42)." Finally, `void (*print_function)(char *message)` means "`print_function` is something that can be dereferenced, yielding somthing that can be called (a function), which takes a single argument - given the optional name '`message`' - which can be dereferenced to give a char, and returns nothing (`void`)." Of course, function pointers don't actually need to be dereferenced to call the function they 'point' to, but the `*` differentiates between function pointers and ordinary function declarations. Having said all that, I agree it's kind of weird, and could be avoided if C used different syntax for declaration (new languages probably should).

@1over137 Рік тому

A word of caution. You may be tempted do void* or char* cast your pointers to get past some funky type casting foo, but be warned, if you wish to enable compiler optimisation, it will refuse to optimise code that's be obfuscated (to it) this way. It need to have concrete, validatable frame pointers for the variables. It's not stupid and will fail on a void* and in cases where it sees you casting a char* back to a somethingelse* it may fail too. I say "caution" as fixing this later in any size of code base will ruin you month.

@estebanzavala9533 6 місяців тому

using a double pointer to create two dimensional structures(rows, cols) has been one of my favorite things to learn in college so far, and it goes deeper when you figure out you can create other pointers to increase the size it gets crazy

@MSDjMichaelSlash Рік тому

THANK YOU! It surpises me how can a teacher introduce this concept without explaining it at university. This was a life saver

@sudiir12345 Рік тому

One of the best explanations I have seen so far

@dabdoube92 Рік тому

Okay what what is THE best one you've seen ?

@AndrewTSq Рік тому

The only thing i missed was WHY you would use pointers. I have no clue and would love to learn. This sounds just like same variable has different name, sounds more confusing to use than anything else.

@itellyouforfree7238 Рік тому

@@AndrewTSq why do we use street numbers? also, he explains it in the last part of the video. have you watched it? you cant just "pass variables to functions". either you pass the object itself by value, or you pass the address where it is stored in memory. what's difficult to grasp?

@AndrewTSq Рік тому

@@itellyouforfree7238 to see where we are? and if we are at the right address? Do you mean pointers are to get a variables memoryaddress? but why would you want to use that instead of just using the variable?

@o-manthehuman7867 Рік тому

I learned pointers by starting out with JS, then learning about how computers work on the low level, then learning cpp, and trying out pointers. By then it was relatively intuitive lol

@GamingMashed Рік тому

that may be because JavaScript doesn't have pointers

@peace_truth1471 Рік тому

Pointers made easy by lll! Loved the video and suddenly everything became a lot clearer! Ty :)

@yudzu8820 Місяць тому

Really good work bruh!!! Everything is explained slowly and step-by-step, word-by-word

@Dewaxel Рік тому

5:13 You can also say that if there was no asterisk, you would put the value of the pointer pX, which is a memory address, to the variable Y. You want the value of that memory address, so you put the asterisk there.

@yash1152 Рік тому

> _"if there was no asterisk, you would put the value of the pointer pX, which is a memory address, to the variable Y"_ which would cause issues

@proloycodes Рік тому

@@yash1152 why?

@yash1152 Рік тому

@@proloycodes i dont remember the specifics, try compiling with the compiler flags _-Werror -Wall -Wextra_ and see, it will tell you.

@DavidSmith-bh6ez Рік тому

- int isn't necessarily 4 bytes, do not ever assume this, use int32_t if you want 4 bytes - using p as a prefix is not a good habit. it originates from a misunderstanding how hungarian notation works. it doesn't add anything, we have had editors that can show you types for years and years now - the age example misses the point that modifying a copy wouldn't do anything - stuff that goes onto the stack is NOT static. it is automatic. static memory either uses the static keyword within a function or is defined outside a function. also an automatic allocation doesn't need to have a statically (at compile time) known size, VLAs do exist

@choobie8486 6 місяців тому

Watching this before my C++ exam, was stressing hard bc it’s all pointers. It’s so easy now! Thanks bubba

@MegaMech Рік тому

Seeing pointers in memory view is really helpful to visually see what's going on.

@remingtonward5356 Рік тому

I want to add, for people trying to understand why the * usage is different when by a type. It's not. The asterisk just isn't by the type, its by the name. int * x; is not saying x is an int pointer, its saying that dereferenced x is an int. This helped me immensely when I realized it, and it explains: int * x, y; makes x a pointer and y an int since y isnt dereferenced but x is in the declaration.

@Spartan322 Рік тому

The thing that always bugs me about pointers in C++ isn't complexity or their memory side effects, but the symbols, I know what everything does, but I always confuse the symbols because & has at least 3 different functions as a singular symbol depending on where you put it (bitwise AND, make a variable a type reference, or a get reference operation) as does * (multiply, make a variable a type pointer, or a dereference operation) and it makes reading the code for me a super pain in the ass. I'm totally comfortable with pointers, I just hate the syntax for them.

@po1sonseede9001 Рік тому

Dyslexia makes it worse trust me.

@Spartan322 Рік тому

@@po1sonseede9001 Yeah I bet, other stupid thing that makes it doubly confusing in C++ is that neither of those symbols apply to the statement as a whole, only to the identifier, so instead of writing: int* p_1, p_2, p_3; you gotta write: int *p_1, *p_2, *p_3; even though an overwhelming majority of cases you will have multiple pointers being declared at the same time. Conventionally you would see int* as a type, but for some reason in C and thus C++ int is the type and the *p_1 defines a modification to the type exclusive to the identifier that isn't shared with any other object declaration in the language. Only contributing to C/C++'s anti-intuitive nature.

@po1sonseede9001 Рік тому

@@Spartan322 I think what bothers me is everyone wants a C/C++-Like syntax nowadays, completely disregarding if the syntax is intuitive.

@Spartan322 Рік тому

@@po1sonseede9001 Yeah, everyone keeps trying to copy C/C++ in such a manner that makes it still a pain in the ass, I wouldn't mind new languages taking a lot of the clean parts of C++ and implementing them in a more readable fashion, but for some reason instead we get Rust and Zig where they try to retain a high amount of C comparisons but you need to declare the variable and then the type alongside all these other things that honestly just feel like a snub at C and C++. Like why are we going back to pre-ALGOL mathematical type specifications? In almost every case the type is necessary information and you still need a structure to a declaration of variables, its cleaner to integrate the type into the declaration then making it look like an addon to the declaration. Its even uglier for functions.

@yuriytheone 11 місяців тому

You just don't know C/C++... Dont lie to us and to yourself... 😅

@danielschmechel9889 Місяць тому

Wtf man this is way easier than I thought, I was having such a hard time to understand pointers. Love you ❤

@Golipillas Рік тому

Great Channel, simple explanations just a great video overall you've earned a subscriber

@ScottySR Рік тому

While pointers as a concept is easy, I think it's rather the C and C++ syntax that creates most of the confusion. Even the 6502 has few addressing modes that use pointers, and they weren't that hard to understand when I was learning them.

@v01d_r34l1ty Рік тому

What may be worse is that C++ reads RTL and C reads LTR. const char* x in C is a constant character pointer, const char* in C++ is a pointer to a character constant. Lol

@RuiShu Рік тому

I think the biggest source of confusion is the syntax and why we need to specify the data type when declaring a pointer. Very often, I see people explaining pointers by emphasizing where the data begins (i.e. the address) but not where the data ends!

@Mallchad 6 місяців тому

That's because pointers have very little care for where the data ends that on you to manage. at best a pointer will use its type to figure out the end of the first element but that feels more like syntactic sugar in C. it will quite happily ignore it if you even so much as implicit cast

@MortalVildhjart 7 місяців тому

Thank you for the very well paced and clearly explained video.

@basaratali92 Рік тому

amazing video, you delivered pointer concept with easy example. impressive

@hdufort Рік тому

I've been programming on the 6809 chip where pointer indirection is built into the instruction set. To me it's clear and makes sense. However I get super confused as soon as I try to apply that understanding to C or C++.

@Double_T_G Рік тому

You mentioned double pointers and array pointers but didn't dive into them at all. You should make a part 2 on that.

@Nightwulf1269 Рік тому

To grasp that topic it is really helpful to generally know how the (at least abstracted) hardware of a computer works. I've been lucky enough that I've been raised in the 80s, so I learned on computers where you needed to know how it works internally to program them. That creates a visual idea of what variables and pointers are. In C and C++ it can be even harder because you can even calculate with pointers. In other languages they exist for the same purposes explained in this (excellent) video but you can not calculate with them (Go e.g.). And languages like Java do have them only under the hood and you sometimes get an idea they exist internally when you hit something like a "NullPointerException". Perhaps you want to create a follow up video explaining pointer arithmetics and how they look in other languages? Thx for the good work!

@cptjpk Рік тому

Appreciate this as I'm learning C in an apprenticeship now. Thanks!

@Bonfi96 Рік тому

Great video! Not sure if it's just me, but I would suggest to change font for some of the examples as the ; looks too much like an i

@LowLevelLearning Рік тому

Thanks for the tip!

@Asdfgadv33423 Рік тому

@@LowLevelLearning Song name, pls?

@andre0baskin Рік тому

I've never found pointers to be all that difficult. This may well be the result of learning PDP-11 assembly with its register addressing modes before any high level languages that supported pointers.

@SerBallister Рік тому

To be fair, in assembly the ONLY way to read/write things in memory is using a pointer, you have little other choices. Assembly programmers should be fluent in using pointers.

@fghsgh Рік тому

@@SerBallister Assembly programmers also understand that types don't exist and pointers are literally just integers, which is imo what makes the most difference.

@CommanderBalok Рік тому

I don't remember them being that difficult, either. But I have been writing software for quite some time, now. It's possible they were, when I was learning. What concerns me is that people now seem to want to write code without actually understanding what the machine does with it. That's how you wind up with buggy, vulnerable, bloated and slow software. Of which there is a great deal.

@Meow_YT Рік тому

Yeah, I came from 6510 and ARM assembly and never had a single problem with them. Didn't even know the terminology, just used them.

@valizeth4073 Рік тому

@@fghsgh That comes with a down sides though, people make false assumptions about the languages. In C/C++ pointers aren't just integers and types are very real, to the point where you very easily invoke undefined behavior. People think of C/C++ in terms of assembly when the two have nothing in common, they target an abstract machine, not your hardware.

@michalkorsak9726 Рік тому

IT WORKED, THANKS I'VE BEEN LOOKING FOR THIS FOREVER, BUT NO TUTORIAL COULD EXPLAIN IT AS YOU DID

@symere1529 Рік тому

such a underrated channel holy shid ive never found someone who can explain this good and easy

@LostSendHelp_YT 4 місяці тому

NASA said don't use pointers

@RagHelen Рік тому

Every video about pointers I have seen so far has given an explanation of pointers which is exactly the definition of variables.

@andrevrey Рік тому

Dude, thank you. This helped me a lot.

@misraaditya9213 Рік тому

Personally, I didn't have much trouble understanding the concept of pointers and how to use them in C, but a lot of people get thrown off by the fact that the * doubles (pun not intended) as both a type-specifier for a pointer (in an expression like int* or char*) and the dereference operator (in an expression like *p += 1)

@casualoutlaw540 Рік тому

Copying from another one of my replies, That's the beauty of it, try formatting your code like int *foo; This basically means foo is a pointer, and you can access the value with *. It also reduces confusion with int *foo, bar; Here bar is an int, foo is an int pointer. This would be a lot more confusing if I wrote it as int* foo, bar; which'd make it seem like int pointer is a type, and foo/bar are instances.

@misraaditya9213 Рік тому

@@casualoutlaw540 Yeah that's a useful formatting tip about keeping the *s with the names.

@Profphizx Рік тому

Great video! Can you give a more advanced tutorial, like using pointers with arrays and functions?

@tusharchilling6886 11 місяців тому

I was very fascinated by the pointers concept when I was studying it. When I studied its application in Linked List, I was so amazed to see its applications. The concept is just amazing.

@namandevnani9648 8 місяців тому

Thank you very much for clearing the concept ❤

@VixieTSQ Рік тому

I only learned about pointers when I learnt my second language, Rust. I never actually had problems with pointers that much (or Rust really just calls them references, when you say pointer in Rust you are normally referring to a raw pointer.) The syntax is just so easy to understand! And it automatically dereferences for you

@waynezor Рік тому

References also exist in C++ and are not the same as pointers. There's the auto dereferencing you mentioned and also you can't reference another reference, while you can have a pointer to another pointer.

@VixieTSQ Рік тому

@@waynezor in rust references reference other references all you want... although you don't normally have much reason to. To me references have always just been raw pointers but they have guarantees about mutable aliasing (and auto deref). Casting a reference to a raw pointer in rust is a NOP I believe. Does C++ have the same no mutable aliasing guarantees?

@sudovon6531 Рік тому

@@VixieTSQ Let me know if i'm wrong but in Rust you can't have two pointers to the same address because of the one owner rule, when you points to another variable address then the original variable loses the context and dies.

@VixieTSQ Рік тому

@@sudovon6531 pointing != ownership. With rust references you can either have multiple immutable reference or one mutable reference to one value. But pointers in rust are diferent and not commonly used. They require an unsafe block to dereference because you can do whatever you want with them. You can delete all the pointers and let the value leak. You can delete the value and dereference a null value. It's scary stuff.

@nightingale3715 Рік тому

For the algorithm. Excellent channel btw!

@LowLevelLearning Рік тому

Welcome aboard!

@ntdash2153 Рік тому

I haven't started the C language yet but understood pointers... thanks 👍

@Dan-ug7zc 7 місяців тому

need more video like this format

@homelander4881 Рік тому

6:49 "malloc failed bruh" 🤣

@asdf7219 Рік тому

Error: segmentation fault (core dumped)

@anon_y_mousse Рік тому

Simple and easy to understand. I wish this had existed 25-ish years ago when I first learned about pointers. Would have made it so much easier to understand. I'm glad I stuck with it though, because now it's fun to write functions to do single allocations for 2d and 3d pointers and set it up for the user of that function. Well, if anyone actually uses it, but it was fun writing and debugging anyhow.

@CrjaseMechaEngr Рік тому

How did you know I needed this!? - That beutiful youtube algorythm

@pyrytheburger3869 Рік тому

damn i didnt understand a thing you said... so glad i work with a language without pointers

@fullaccess2645 Рік тому

bruh

@pol165 Рік тому

lol

@AMildCaseOfCovid Рік тому

I think the hardest part about pointers is just the syntax. Using the * to create a pointer variable and also using * to dereference the pointer to get the value is confusing

@casualoutlaw540 Рік тому

That's the beauty of it, try formatting your code like int *foo; This basically means foo is a pointer, and you can access the value with *. It also reduces confusion with int *foo, bar; Here bar is an int, foo is an int pointer. This would be a lot more confusing if I wrote it as int* foo, bar; which'd make it seem like int pointer is a type, and foo/bar are instances.

@Vinxian1 Рік тому

I think it's more confusing that * is both used for multiplication and pointers. & Is used for bitwise operations and creating a reference. Why not use different symbols?

@4rtur680 5 місяців тому

Thank you bro, you really saved my desire to continue learning C++

@absmustang Рік тому

pointers are easy to learn and even easier to forget. i’m keeping this one on my fav videos for next c project

@maxfiialkovskyi5346 Місяць тому

u know arrays, right? well, all of memory is an array. a pointer is an index of this array. yup, thats it.

@HUSS_BOSS Рік тому

who else watched the video and still confused ? 😂

@eminem992i Місяць тому

lol same

@diegodisena Рік тому

This is the better video programming content I have never seen, simply insane good.

@MoolsDogTwoOfficial 24 дні тому

Before I did week 5 of CS50 I had the impression that complex data structures just need arrays/lists and that’s it. But now I realise how bloody amazing these things really are. The fact you can link multiple things together all using pointers was such an eye opener when it comes to programming.