Pointers in C for Absolute Beginners - Full Course
Finally understand pointers in C in this course for absolute beginners. Pointers are variables that store the memory address of another variable. They "point" to the location of data in memory. With a bunch of examples, this course demystifies pointers and their various uses, covering topics such as passing by reference vs. value, void pointers, arrays, and more.
✏️ Course created by @onaecO
⭐️ Contents ⭐️
(0:00:00) Introduction
(0:00:39) What is a computer eli5 CPU, RAM, bytes
(0:08:04) Data Types
(0:13:31) Intro to processes
(0:16:44) process memory layout
(0:19:17) Variables in memory
(0:23:01) Naive change_value program
(0:28:05) Change_value with pointers
(0:33:03) The classic swap
(0:34:05) Why declaration and dereference have the same syntax for pointers?
(0:38:39) Advantages of passing by reference va passing by value
(0:45:26) Why do pointers to different data types have the same size?
(0:47:49) Given that pointers have all the same size, why do we need a pointer type?
(0:58:16) void pointers are confusing
(1:00:14) why malloc is handy and more on void*
(1:09:09) Are arrays just pointers?
(1:25:00) Array Decay into a pointer
(1:32:59) why array decay is useful?
(1:37:49) arr[5] == 5[arr]
(1:39:04) pointers to pointers: **argv
(1:47:11) *argv[] or **argv?
(1:52:41) pointer to functions
(1:59:02) use case with pointers to functions
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Пікірлер: 181
I loved it! I sat down and typed the whole thing and every exercise and this helped a lot. The explanations and examples are really good, I learned a lot even if I thought I was not a total beginner. :)
Amazing video, with extremely clear explanations of what pointers are and how to use them. Thank you very much!
I just started learning C/C++ and this gets dropped, definitely you guys are amazing, thank you for the course! This is really helpful
@UToobUsername01
Жыл бұрын
I used to learn C and it got me back into wanting to re-learn all of the stuff I forgot. I think I have many "learn how to code in C" books lying around but I ended up stopping right about the part where it got into pointers. lol
@nkazimulojudgement3583
Жыл бұрын
@@UToobUsername01 you dont work with C anymore?
@beepbeepgamer1305
9 ай бұрын
are you still learning c? I just started learning c since there's an paper for c in my clg. C is tough ngl, how is it going on for you?
@armincal9834
8 ай бұрын
@beepbeepgamer1305 imo c is actually the easiest language there is,but because it's so simple,writing anything more complicated than a text manipulation program is a pain because the language almost doesn't do anything for you
This is just the best course about pointers that I found online! 😀
Great class! Just finished it, pointers explained with mastery, thanks!
So anyway this is the best C Tutorial on KZread…. Well Done!!! 👏🏽 👏🏽 👏🏽
Awesome masterclass! Really well explained and very comprehensive, thx for this content!!
Brilliant, very well explained. Thank you for sharing your insight.
Hooray! Thanks for lession.
I loved this! I finally understood the pointer concept. Thank you for this.
Interesting and informative video to watch - thank you very much!
one of the best videos so far.
The first 40 minutes was all it took for me to understand this concept of pointers clearly. Great Tutorial!
@Abdallah..................
5 ай бұрын
The same. I understand this concept after watching the first 40 minutes of the video
I have just watched this video. And I would tell you that you got a new follower. Such a great video. Also the site you mention to visualize how pointers work. I really advice people to watch this video and to be patient. According to me. I understand the whole idea about pointers by the first 40 minutes.
As a computer science engineer I can see how understanding pointers pavement you to understand the underneath meaning of variables, arrays and complex structures. That's something that we all are forgetting with 'modern' languages.
@sarahyukino7213
Жыл бұрын
I learned about 'pointers' with rust, don't know if it's the same thing with C
@Aryan_Divyanshu_000
Жыл бұрын
Interesting
@joshuaketor
9 ай бұрын
Very true
Thank you for the amazing lecture!
wow, it makes me understand things! Thank you!
Brilliant video. Also subbed and clicked the bell. Waiting for your next video.
Wow! Running the program at the visualization site, we can visually see how the pointer is working. Great! Thank you for the insightful lecture.
C is a classic language never get old evergreen thank you once more FFC
@SS-jq6mh
Жыл бұрын
FreeFodeCamp
@iGhostr
Жыл бұрын
@@SS-jq6mhlmao 💀
Very good tutorial. Could say it's the best on the market and it's free. Would gladly donate
This is very helpful thanks.
As someone who learned pointers at university, I found the video really useful, especially the introduction about computer memory. In my opinion, it's not really dedicated to "Absolute Beginners". Thanks for your efforts.
Thank you very much for this content!
Love C and C++. Instant like and love to the video
I appreciate your work thank you so much for your video
Simply the best 👌
Great tutorial
Informative ❤❤❤
Really good at explaining memory, like a professor
Thank you.
This help students alot because pointers is difficult for students in programming
thank for these pointers, Goodç7
All the Code used and few notes here: medium.com/@jalal92/just-dereference-the-link-for-the-code-in-the-video-cdfc0c2d9547 I learnt myself a lot with freeCodeCamp and now, crazy enough, i produce myself tutorials! I will always be a promoter of this amazing project, empowering people for free all over the world. A particular mention to Beau that allowed me to be part of this, such a gentleman! ❤
This is gold
1/2 Some key notes (not detailed and please correct my understanding where necessary): The main function is BOOM the big bang of the program where the code starts executing. This function sets off a chain of calls and returns from other functions. Nice diagram at 16:24 Naive change_value program (code at 23:02) -nb is an int variable set to 42. the nb variable is passed to the change_value function. Within the change_value function, nb is set to 1337. Now in the main function, nb is printed. What will the value of nb be? - The answer is nb will still have the value of 42. Why? This is because the variable nb is passed by value and not by reference. Basically a copy of the variable is passed to the change_value function rather than the memory address where the variable is stored. This means that change_value changes the value of a copy of nb to 1337 rather than the original nb variable. change_value program with pointers (code at 32:45) -So how would you change the original nb variable? -The answer is to pass a direct reference to the nb variable address AKA a pointer! -The code is changed such that change_value's parameter is a pointer (designated with asterisk (*) before variable name), the variable name is changed to foobar -*foobar is assigned the value of 1337 (The variable stored at the foobar pointer is assigned 1337) (foobar refers to the pointer that stores the address while *foobar refers to the variable stored at this address; referring to the variable stored at the address is called dereferencing) -Instead of creating an nb pointer in the main function the nb address can be passed directly as &nb -Now nb is successfully changed to 1337! We are dealing with the same nb variable stored in the same memory location rather than a copy of the nb variable! Classic Swap (code at 33:40) -a is an int variable assigned 42. b is an int variable assigned 1337. swap is a function that will switch these values using pointers. First, the addresses of a and b are passed to swap as parameters. -In the swap function, a is referred as n and b is referred as n1 (based on order when swap is called). -To swap the values, the int variable tmp is created to temporarily store n's value. n is then assigned n1s value. Finally, n1 is assigned n's original value. -Line 7 n is dereferenced, Line 8 n and n1 are dereferenced, Line 9n1 is dereferenced. Dereferencing simply means dealing with variables rather than the memory locations where variables are stored Why declaration and dereference have the same syntax? (34:05) -Worth watching this section, it is concise The main benefit of passing by reference is that you don't need to make a copy and therefore you save memory especially if you are passing something large like a large array Pointers have the same size for different data types, an analogy for this is that the empire state building address and a small restaurant's address are the same size, even though the size of the buildings are different If pointers are the same size, why do pointer types have to be specified? (pointer type = type of variable achieved by dereferencing pointer) Basically, different different data types are stored differently in a way that impacts pointer functionality. chars take up 1 byte, ints take up 4 bytes. (One memory address correlates to one byte) One example of how functionality is changed is pointer arithmetic: if pc is a char pointer (chars are 1 byte, a memory address holds 1 byte), and pc refers to the memory address 0x7ffeea5f930, pc + 1 would refer to 0x7ffeea5f931, pc + 2 would refer to 0x7ffeea5f932 if ptr is an int pointer (ints are 4 bytes, a memory address holds 1 byte), and ptr refers to the memory address 0x7ffeea5f930, pc + 1 would refer to 0x7ffeea5f934, ptr + 2 would refer to 0x7ffeea5f938 Pointers can be type casted (the pointer type is changed) line 13 in code at (50:57) which changes how the compiler interprets the variable stored in the pointer. Basically the pointer can act like the variable it is associated with is of a different type, while the actual variable is unchanged. I know this is confusing, please call me out if I am wrong about anything. As stem cells can become any cell type, or actors can be assigned any role, void pointers can later be assigned a data type.
Thank you, my friend =)
very good
Do you have a video with generic pointers and memory by increment, also data structures with generic pointers.
2 hours of lectures about pointers? Most videos are like 5 mins and I feel that they do not help at all this is great!
감사합니다.
Saved the video for first year at university
Thx ❤
Best programming channel ever!
This ma mannn right here !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! thx a lot cuh ))))))))))
The very topic why I left c .now I am gonna try again ❤
@user-bw6sr5bj7e
Жыл бұрын
"C and assembly are great starting points in the world of programming."
@benjwilliams5104
10 ай бұрын
Best of luck! You got this!
Todavía no he visto el video pero en las explicaciones de pasar arrays a las funciones te ha faltado el caso del array de más de una dimensión, que en este caso sí hay que pasarle todas las dimensiones menso la primera a fin de que cuándo se haga uso del array dentro de la función éste sepa dónde buscar el dato. Por ejemplo: void (int my_array[][2], sizeof_t size) { ... }
@onaecO
Жыл бұрын
Dear friend, you are totally right. The thing is that i thought about super beginners in this video-course. I rarely use 2D matrixes in real life, furthermore i don't wanna scare too much with too many details. This concept i'd say is for more advanced users. Here i just want to bring someone from 0 to 1 with pointers.
I’m at 30 mins so far. So basically we just have to use the & sign when we pass variables in as arguments, and in our functions we use * to declare a pointer and deref inside the function. This way we can actually change the value of our original variable. Is that right?
We also need a handlebars(hbs) tutorial as it will be very helpful since there is no tutorial for hbs in YT.
This tutorial just dropped at the right time.
Thanks for the video! Funny that in the compiler I have, gcc that came in my ubuntu distro, the example at around 59 minutes leads to a segmentation error, it does not print the int 42. Printing the address I see it is (nil), so it seems that when the stackframe for foo goes away the pointer is nil. I am not sure though if this happens because the compiler assigns nil to any function that tries to return an address to a local variable or else?
Your videos have helped me so much!
@haniissa1990
Жыл бұрын
how his video helped you if you just watch less then 10 minutes? and the video uploaded before 11 minute?💩
@ascendedbox612
Жыл бұрын
@@haniissa1990 I didn't watch this one? I used his python playlist. Why are you so argumentative?
I don’t understand how you guys always know what I’m Googling.
@techdoctorP
Жыл бұрын
Brooooooooo.... It's wild..
@rusi6219
7 ай бұрын
They're in your walls
It's rather useful to rewind the video if you do not understand. A random passerby
Grazie
You could enable close captions.
i have finished c exam yesterday and saw this video today :(
Long live C 🔥
love the subtle graphics used in the explanation
At 31:25 you say everything works thanks to the power of pointers, but in the slide, the initial value is the same as the one you are changing it to ... I mean, it works like you say, but the initial value is identical to the changed value not sure why you changed it from 42 on the previous slide ... don't forget to get your slides reviewed
C IS HIGHLY EFFICIENT!
why there is turing picture in the backgroud in ide ?
Thanks for the video! Can someone explain, at 32:47, why do we need line 3? The function change value is already present at line 14 onwards.
@zDoubleE23
4 ай бұрын
Line 3 is called a “prototype.” Notice that when used in main(), change_value isn’t defined until line 14. This would cause the compiler to reject the code. So using a prototype allows programmers to define the function before main() in order to avoid this error. Note that prototypes require the “;” whereas creating the function does not.
I just spent today reading chapter 5 of K & R's C programming and this video came 😂....such a weird coincidence
@_powerbeard
Жыл бұрын
Best language book and it's not even close. Although Borland Turbo C Bible was useful.
@CabernetKing
6 ай бұрын
Idk how you got through K&R that book is absolutely atrocious
great that it has dark background!
Can someone please explain how he got 0100 at 1:08:45
that course is something different and and an amazing course i hopefully could finish it as soon as possible and thanks freecodecamp
Am I the only one curious about his vim setup. please how did you do that ?
I want to learn software engineering on KZread, can I get recommendations and scheme for this?
Good tutorial but why you don't activate subtitle cc
i love C
I almost forgot C even had pointers 😂.
@theencryptedpartition4633
Жыл бұрын
How did you not C dat?
@lasruomabdjan4904
Жыл бұрын
😅😅😅😅😅😂
@nocopyrightgameplaystockvi231
Жыл бұрын
@@theencryptedpartition4633 was busy tangling with 🐍
@bresent
Жыл бұрын
How do you use C then?
@in.meraki
Жыл бұрын
Nobody pointed out the pointer to you?
Again thanks for the video. By the end there is this example using vmmap, I understand vmmap is only for mac. Is there a similar tool I can use on a Ubuntu machine?
@whyal5307
Ай бұрын
vim
6:45 arithmetic operations (+-/* %) comparasion operations( = != ) logical operations( && ! ||)
O tema me interessa muito, mas o meu ingles é muito pobre - The topic interests me a lot, but my English is very poor
data strcture in c please
could you teach how you turn the gcc and ./a.out code into one function? You named it "r", how do I do that?
@CabernetKing
6 ай бұрын
gcc example.c -o example && ./example The -o part stipulates what you’ll name your program instead of the default ‘a.out’
Can someone explain to me what is const pointers? Is very common to see functions with const pointers as input
@eduardof.vicentini9225
Жыл бұрын
Can we have some examples of these functions, please?
@hugo-garcia
Жыл бұрын
@@eduardof.vicentini9225 void func (const int* p){ // do stuff; }
@vonderklaas
8 ай бұрын
Guys, GPT is out!
@DenisTrebushnikov
5 ай бұрын
I guess you already found the answer, however I try to explain for myself: any pointer as well as any variable has an address in memory cell, the value in the memory cell can be changed... adding word const we deny changing value. So const pointer that link to address can't be changed, you can't assign pointer a new address. (pointer on const value is the different thing - and this means, that with pointer you can't change value by address)
❤
The example with function change_value(int nb) at 23:03 is confusing. Logically one would expect change_value(nb) would chane the value of nb, because nb is declared and initiated (nb=42;) in main() (and therefor is of a global scope) and it is not re-declared within change_value(nb). Therefore nb is visible from change_value(nb). If. as you say, nb mentioned in change_value(nb) is a different variable, then you should get an error "nb is not declared" Will you explain please?
@em_iiy
Жыл бұрын
I think a couple things are unclear to you When declaring a variable in the main function, it's scope is limited to the main function. A global variable would be declared like this: int global = 42; int main() { printf("%d ", global); global = 1337; printf("%d ", global); } this would print out: 42 1337 The other thing is that seems unclear, is that the parameters of a function also declare them as a variable, and initialize them with the value passed to the function this means that: change_value(int nb); int main() { change_value(42); } this creates a new integer variable called nb in the scope of the change_value function, and sets that variable to 42 (or whatever you pass through the function). So in the example the nb variable in the main, and the nb variable in the parameters to the change_value function are unrelated to each other they just happen to have the name Hopefully this clears things up a bit Have fun learning about pointers ;)
@user-vd6wb5ef8v
Жыл бұрын
@@em_iiy thank you for your quick and detailed reply. It is clear with the global example. Yet I still cannot get a clean logical picture about change_value function. Part of the confusion is causes by (int nb) in the function declaration. Should I understand that "nb" in the function declaration and "nb" inside the function definition is just a coincidence? I.e. the function declared as change_value(int any_integer_variable_or_number) would have the same effect? Another confusion: both main() and change_value() are functions. Yet main() requires a variable to be declared before being assigned a value, while change_value() can assign a value to an undeclared variable. Why?
@em_iiy
Жыл бұрын
@@user-vd6wb5ef8v Yes you're correct that the 2 "nb" variables are coincidentally called the same name but are entirely different variables. They could've declared the function like "void change_value(int x)" and it would've done the exact same thing. my guess is that it is a setup to introduce a change_value() function that does do what you expect but by passing a pointer instead, so the confusion was likely done on purpose (I can't say this for sure as I've not actually watched the video). In case they haven't I put the code to something that would work at the end of the comment Your 2nd question might be a tiny bit tricky to explain but I'll try my best. In the change_value(int x) function, the variable "x" gets declared in the parentheses. so if you were to try and declare "x" again in change_value, like "int x = 100;" you'd be left with an error. This "parameter" is then immediately assigned whatever you passed to the function, be it the value a constant value or the value assigned to a variable. ex: int a; a = 42; change_value(42) // here a constant value of 42 is passed to the function change_value(a); // here the value held by "a" is passed to the function, which happens to be 42 what you can imagine happening in the change_value function in both cases is: change_value() { int x = 42; // or whatever value you passed through x = 1337; } so the variable is declared, just in a slightly different way. Keep in mind that C tends to keep throwing you in the deep end with very low level concepts, which can be quite difficult to grasp. However these concepts become easier and easier the more you play around and just make stuff, and you'll start noticing that they give you a ton of control over whatever you're creating. They also give you insight on how a computer works in general which is very useful outside of just C. So don't worry about not getting them immediately. I hope what I wrote wasn't too confusing, I'm more used to explain these things verbally so this is a good exercise for me as well. Working change_value program: // function takes a pointer to an integer value void change_value(int *ptr) { *ptr = 1337; // the function dereferences the pointer to change the value of the variable it's pointing to } int main () { int nb; nb = 42; printf("%d ", nb); change_value(&nb); // now passing the address of nb rather than just the value printf("%d ", nb); } done this way it should now print: 42 1337
Does stack grow top to bottom or bottom to top ???? Chatgpt says that it grows from bottom to top .
@tesfalemeshetu4675
5 ай бұрын
Top to bottom for stacks , and bottom up for heaps
Someone needs to show this to CrowdStrike Developers.
Thanks guys will you arrange a session about crack games/softwares?
First 'comments on this lecture ❤
what does that 1337.42 mean :)
Thank you for the lesson, but the fonts and shapes used in the education materials are very poor.
👍
Yes 🎉 1st
35:00
I don't understand the joke between bit nibble and byte. 7:10 can someone explain? I am not a native speaker. What is that mean '4 bits are enabled'
@priyaghate522
9 ай бұрын
when we just nibble at food when we arent that hungry.. thats called nibble and when we really feel hungry we bite the food .. thats what hes trying to say.. nibble and bite (byte) is sort of related to food analogy, i hope you understand what im trying to say :)
Sadly watching this on a phone is basically impossible because of the images and color use. Guess it gottta be on a pc screen
I wait Django course
38:31
anyone know how to run code in terminal just like that guy did ?
@siddhantchavan1370
10 ай бұрын
thats vim and he is using command for compiling, rather than pressing run on ide's like visual studio, you first compile the program and run the executable. Search on google how to compile using gcc compiler.
@boody8844
10 ай бұрын
gcc code.c and then run a.exe
13:32
8:04
I wish the author uses emglish phrasing im a more standardized way. It would be more clear what he wanted to explain.
I know less about pointers now because of this video, very confusing.
who is the lecturer of this video??!
I'm piscine 42 ecole this moment.