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.
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
@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
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.
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. :)
Timestamps 00:05 - Pointers are variables that store the memory address of another variable. 03:14 - A computer is an arithmetical, logical calculator and a storage for numbers. 09:11 - Integer types and real types have a different way of encoding in memory. 12:00 - Introduction to pointers and computer architecture 17:45 - Pointers in C allow you to manipulate memory and retrieve control back after performing operations. 20:34 - Addresses in memory are represented as bits and the stack is used for function allocation and deallocation. 26:08 - Pointers in C allow us to change the value of a variable in a different function by passing its address. 28:59 - Pointers in C allow you to reference and manipulate values in different memory locations. 34:42 - Understanding the notation of variable declaration in C 37:37 - Pointers in C allow for efficient manipulation of memory and data 43:04 - Passing a value by reference can be more efficient as it avoids copying all the data every time 45:53 - Pointers in C allow us to point to objects in memory, irrespective of their size. 51:16 - Pointers in C allow for interpreting binary data in different ways based on the data type. 53:42 - Pointer arithmetic in C allows you to manipulate memory addresses and access data based on the type of pointer. 59:16 - Understanding void pointers and their role in interpreting generic data 1:02:00 - Using pointers in C allows for memory allocation and accessing data in a more controlled manner. 1:07:22 - Void pointers in C allow for generic pointer arithmetic. 1:10:08 - Understanding the relationship between arrays and pointers in C 1:16:08 - The main difference between arrays and pointers is that you cannot perform pointer arithmetic directly on the pointer itself 1:19:22 - The size of a pointer is different from the size of an array 1:25:09 - Arrays and pointers behave similarly in C, sometimes acting as arrays and sometimes as pointers. 1:28:09 - Arrays in C can decay into pointers, allowing pointer notation to be used to access array elements. 1:33:58 - Passing arrays as pointers in C allows for flexibility and reduces memory usage 1:37:01 - Understanding array and pointers in C 1:42:56 - Loop through the characters of a string until reaching the null character 1:45:48 - Notation and square bracket notation are more intelligible for understanding the structure of arrays and pointers. 1:51:54 - Pointers can be used to create complex structures and manipulate memory addresses. 1:54:11 - Functions in C are stored in the text area of memory. 1:58:40 - Understanding pointers to functions 2:00:55 - Pointers to functions in C have to be consistent and match the signature of the function
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.
This is AWESOME. Very concise, excellent video. Well organized and jam packed with golden nuggets of interesting and relevant information. Keep up the great work!
I've finished 2 4 hour C courses, 6 hours into a 10 hour C course, and 4 hours into an 18 hour C course, also I'm in week 3 of cs50x. I can already tell that this is gonna be one of the more useful ones.
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?
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.
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! ❤
@@marbasfpv4639 you got to thank God for the blessings he gave you like the ability to understand a complex subject such as pointers. my comment was to mark that i have already watched this so i dont forget and watch it again in the future.
One of the best ways to think about pointers in C/C++ or any other language that makes use of them through hardware to software interfaces and ABIs is to think of them as a fixed size unsigned integer or integral value. That's really all they are. They contain an integer value. Yes, they are a named variable and yes, they do point to a memory location or address either being a physical or virtual location, yet fundamentally they are in their simplest form a number with a fixed bit - byte representation. They are either typically 1,2,4,8 bytes in size and on some more powerful systems even 16 and 32 bytes in size where those bytes in most cases are 8-bits. They are just sequences of binary values of 0 and 1 that can be both arithmetically and logically manipulated and evaluated. It's that simple.
i have been learning c for a couple of days bc i know the basics of coding and programming and i learned c in 2 days and i feel good so i am learning about pointers now to make more progrerss
1:29:00 difference between arrays and pointers: when you work with arrays, you have an object allocated in the stack and this is different from a pointer. An array is not a pointer.
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.
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) { ... }
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.
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?
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?
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 ;)
@@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?
@@Андреич-с4н 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
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?
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
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)
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 :)
![Pointers in C / C++ [Full Course]](http://i.ytimg.com/vi/zuegQmMdy8M/mqdefault.jpg)
![Pointers in C / C++ [Full Course]](/img/tr.png)
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.
I just started learning C/C++ and this gets dropped, definitely you guys are amazing, thank you for the course! This is really helpful
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
@@UToobUsername01 you dont work with C anymore?
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?
@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
The first 40 minutes was all it took for me to understand this concept of pointers clearly.
Great Tutorial!
The same. I understand this concept after watching the first 40 minutes of the video
C is a classic language never get old evergreen thank you once more FFC
FreeFodeCamp
@@SS-jq6mhlmao 💀
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.
I learned about 'pointers' with rust, don't know if it's the same thing with C
Interesting
Very true
감사합니다.
So anyway this is the best C Tutorial on UA-cam…. Well Done!!! 👏🏽 👏🏽 👏🏽
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. :)
This is just the best course about pointers that I found online! 😀
Timestamps
00:05 - Pointers are variables that store the memory address of another variable.
03:14 - A computer is an arithmetical, logical calculator and a storage for numbers.
09:11 - Integer types and real types have a different way of encoding in memory.
12:00 - Introduction to pointers and computer architecture
17:45 - Pointers in C allow you to manipulate memory and retrieve control back after performing operations.
20:34 - Addresses in memory are represented as bits and the stack is used for function allocation and deallocation.
26:08 - Pointers in C allow us to change the value of a variable in a different function by passing its address.
28:59 - Pointers in C allow you to reference and manipulate values in different memory locations.
34:42 - Understanding the notation of variable declaration in C
37:37 - Pointers in C allow for efficient manipulation of memory and data
43:04 - Passing a value by reference can be more efficient as it avoids copying all the data every time
45:53 - Pointers in C allow us to point to objects in memory, irrespective of their size.
51:16 - Pointers in C allow for interpreting binary data in different ways based on the data type.
53:42 - Pointer arithmetic in C allows you to manipulate memory addresses and access data based on the type of pointer.
59:16 - Understanding void pointers and their role in interpreting generic data
1:02:00 - Using pointers in C allows for memory allocation and accessing data in a more controlled manner.
1:07:22 - Void pointers in C allow for generic pointer arithmetic.
1:10:08 - Understanding the relationship between arrays and pointers in C
1:16:08 - The main difference between arrays and pointers is that you cannot perform pointer arithmetic directly on the pointer itself
1:19:22 - The size of a pointer is different from the size of an array
1:25:09 - Arrays and pointers behave similarly in C, sometimes acting as arrays and sometimes as pointers.
1:28:09 - Arrays in C can decay into pointers, allowing pointer notation to be used to access array elements.
1:33:58 - Passing arrays as pointers in C allows for flexibility and reduces memory usage
1:37:01 - Understanding array and pointers in C
1:42:56 - Loop through the characters of a string until reaching the null character
1:45:48 - Notation and square bracket notation are more intelligible for understanding the structure of arrays and pointers.
1:51:54 - Pointers can be used to create complex structures and manipulate memory addresses.
1:54:11 - Functions in C are stored in the text area of memory.
1:58:40 - Understanding pointers to functions
2:00:55 - Pointers to functions in C have to be consistent and match the signature of the function
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.
This is AWESOME. Very concise, excellent video. Well organized and jam packed with golden nuggets of interesting and relevant information. Keep up the great work!
This guy is awesome. Throws in jokes too and memes. Best tutorial ive seen in a min
I loved this! I finally understood the pointer concept. Thank you for this.
Hooray! Thanks for lession.
I've finished 2 4 hour C courses, 6 hours into a 10 hour C course, and 4 hours into an 18 hour C course, also I'm in week 3 of cs50x.
I can already tell that this is gonna be one of the more useful ones.
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?
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.
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! ❤
Amazing video, with extremely clear explanations of what pointers are and how to use them. Thank you very much!
تم بحمد الله، اللهم انفعنا بما علمتنا وزدنا علما.
Lol what does any of this have to do anything with some god??
@@marbasfpv4639 you got to thank God for the blessings he gave you like the ability to understand a complex subject such as pointers. my comment was to mark that i have already watched this so i dont forget and watch it again in the future.
@@marbasfpv4639 ولو كره الكافرون
امين، بارك الله فيك اخي حبيبي و نفعك و نفع بك❤
اللهم علمنا ما ينفعنا و انفعنا بما علمتنا
Marvelous Tutorial. I'm a beginner and it helped me very well!
Very good tutorial. Could say it's the best on the market and it's free. Would gladly donate
Wow! Running the program at the visualization site, we can visually see how the pointer is working. Great! Thank you for the insightful lecture.
Great class! Just finished it, pointers explained with mastery, thanks!
The very topic why I left c .now I am gonna try again ❤
"C and assembly are great starting points in the world of programming."
Best of luck! You got this!
This help students alot because pointers is difficult for students in programming
one of the best videos so far.
Saved the video for first year at university
This tutorial just dropped at the right time.
One of the best ways to think about pointers in C/C++ or any other language that makes use of them through hardware to software interfaces and ABIs is to think of them as a fixed size unsigned integer or integral value. That's really all they are. They contain an integer value. Yes, they are a named variable and yes, they do point to a memory location or address either being a physical or virtual location, yet fundamentally they are in their simplest form a number with a fixed bit - byte representation. They are either typically 1,2,4,8 bytes in size and on some more powerful systems even 16 and 32 bytes in size where those bytes in most cases are 8-bits. They are just sequences of binary values of 0 and 1 that can be both arithmetically and logically manipulated and evaluated. It's that simple.
Really good at explaining memory, like a professor
I appreciate your work thank you so much for your video
Awesome masterclass! Really well explained and very comprehensive, thx for this content!!
It's rather useful to rewind the video if you do not understand. A random passerby
i have been learning c for a couple of days bc i know the basics of coding and programming and i learned c in 2 days and i feel good so i am learning about pointers now to make more progrerss
1:29:00 difference between arrays and pointers: when you work with arrays, you have an object allocated in the stack and this is different from a pointer. An array is not a pointer.
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!
Brilliant video. Also subbed and clicked the bell. Waiting for your next video.
This ma mannn right here !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! thx a lot cuh ))))))))))
Brilliant, very well explained. Thank you for sharing your insight.
This is very helpful thanks.
Love C and C++. Instant like and love to the video
wow, it makes me understand things! Thank you!
Simply the best 👌
thank for these pointers, Goodç7
Informative ❤❤❤
Wow awesome video. Thank you for your contribution.
Thank you.
I don’t understand how you guys always know what I’m Googling.
Brooooooooo.... It's wild..
They're in your walls
love the subtle graphics used in the explanation
i knew pretty much all of this but watched it anyways because why tf not
Thank you for the amazing lecture!
Interesting and informative video to watch - thank you very much!
Thank you very much for this content!
Best programming channel ever!
Great tutorial
One of best videos of this topic for me,thx:)
i have finished c exam yesterday and saw this video today :(
C IS HIGHLY EFFICIENT!
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.
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.
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) { ... }
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.
very good
I just spent today reading chapter 5 of K & R's C programming and this video came 😂....such a weird coincidence
Best language book and it's not even close. Although Borland Turbo C Bible was useful.
Idk how you got through K&R that book is absolutely atrocious
thank you my friend.
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?
Thank you, my friend =)
This is gold
Long live C 🔥
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?
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 ;)
@@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?
@@Андреич-с4н 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
Your videos have helped me so much!
how his video helped you if you just watch less then 10 minutes? and the video uploaded before 11 minute?💩
@@haniissa1990 I didn't watch this one? I used his python playlist. Why are you so argumentative?
Someone needs to show this to CrowdStrike Developers.
6:45 arithmetic operations (+-/* %) comparasion operations( = != ) logical operations( && ! ||)
Can someone please explain how he got 0100 at 1:08:45
why there is turing picture in the backgroud in ide ?
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?
vim
Am I the only one curious about his vim setup. please how did you do that ?
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
I want to learn software engineering on UA-cam, can I get recommendations and scheme for this?
We also need a handlebars(hbs) tutorial as it will be very helpful since there is no tutorial for hbs in YT.
Thx ❤
Can someone explain to me what is const pointers? Is very common to see functions with const pointers as input
Can we have some examples of these functions, please?
@@eduardof.vicentini9225 void func (const int* p){
// do stuff;
}
Guys, GPT is out!
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)
Does stack grow top to bottom or bottom to top ???? Chatgpt says that it grows from bottom to top .
Top to bottom for stacks , and bottom up for heaps
Good tutorial but why you don't activate subtitle cc
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'
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 :)
i love C
great that it has dark background!
Grazie
O tema me interessa muito, mas o meu ingles é muito pobre - The topic interests me a lot, but my English is very poor
what is the compiler name and version does he use?
First 'comments on this lecture ❤
Long explanation short: array notation is just syntactic sugar to pointer notation!😎
could you teach how you turn the gcc and ./a.out code into one function? You named it "r", how do I do that?
gcc example.c -o example && ./example
The -o part stipulates what you’ll name your program instead of the default ‘a.out’
here is a pointer, just do it in modern C++ where alot of the problems are handled by the compiler
35:00
Thank you for the lesson, but the fonts and shapes used in the education materials are very poor.
Over 2 hours on just pointers? Now I know why C programmers hate them so much.
I never hated them, but on the Unix side we had core dumps and you could rebuild the program at point of crash.
that course is something different and and an amazing course i hopefully could finish it as soon as possible and thanks freecodecamp
Yes 🎉 1st
who is the lecturer of this video??!