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Dynamic Memory Allocation | C Programming Tutorial 

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An overview of dynamic memory allocation in C. Source code: github.com/portfoliocourses/c.... Check out www.portfoliocourses.com to build a portfolio that will impress employers!

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10 июл 2021

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Комментарии : 137   
@mikehibbett3301
@mikehibbett3301 4 месяца назад
A lovely explanation from someone who didn't come into this field from the early days.
@manobrodeful
@manobrodeful 2 года назад
Your videos are being of great help to me on my Data Structures and Algorithms class at college. You teach very well, thanks very much!
@PortfolioCourses
@PortfolioCourses 2 года назад
You're very welcome, I'm so glad to hear these videos are helping you! 😀
@efilopialul2494
@efilopialul2494 5 месяцев назад
Where are u studying?
@Ch4p1n17
@Ch4p1n17 22 дня назад
Dude, You have helped me a ton more than possible, you explain things so much better than most tutorials out there, Thank you so much!
@PortfolioCourses
@PortfolioCourses 21 день назад
That’s so great to hear, thanks for sharing this, and you’re very welcome! :-)
@DHARMA252
@DHARMA252 12 дней назад
Man I love your channel. Your explanation is clear and consistent so even I can understand.
@bhathiyaranasinghe6637
@bhathiyaranasinghe6637 5 месяцев назад
your teaching way is so clear and easier to listen. Thank you again.
@thekraken2302
@thekraken2302 Год назад
thank you so much for this video i've been struggling with malloc and calloc for the longest time and you were the first one that explained it in a way that i understand Love the channel
@PortfolioCourses
@PortfolioCourses Год назад
That's awesome, I'm very glad to hear this video helped you out. 🙂
@hyperphenomenal4360
@hyperphenomenal4360 8 месяцев назад
this is top quality content, and yet terribly underrated, thank you for your clear explanation!
@PortfolioCourses
@PortfolioCourses 8 месяцев назад
You're very welcome, I'm glad you enjoyed the video! :-D
@al470ex12
@al470ex12 Год назад
You are a legend, it took me hours trying to understnad this from my teacher and books, but you have summed it up for me in 30 (15 because I like to go fast) min! Thank you!
@PortfolioCourses
@PortfolioCourses Год назад
You’re welcome Alex, I’m glad the video was able to help you out! :-)
@0xRAND0M
@0xRAND0M Год назад
You teach very well, Your videos are very helpful, I hope more people realize the quality of your work.
@PortfolioCourses
@PortfolioCourses Год назад
Thank you for the kind feedback Christopher, I’m glad you enjoy the videos! :-) The channel has only been active for 2 years, I’m hoping over time more people learn about it too.
@hirdaybindra5382
@hirdaybindra5382 4 месяца назад
so under rated channel!
@goldbar7779
@goldbar7779 Год назад
This was the only good video I could find after watching several videos Nice job 🥂
@PortfolioCourses
@PortfolioCourses Год назад
I’m glad the video was helpful for you, and thank you for the kind feedback! :-)
@VincentAlesi
@VincentAlesi 4 месяца назад
Really well explained, thank you for the lesson!
@PortfolioCourses
@PortfolioCourses 4 месяца назад
You’re welcome! :-)
@dangeerraaron
@dangeerraaron Год назад
That was an awesome tutorial! I followed along on my text editor + Ubuntu terminal and made clarifying comments (for myself, haha). I found the use of the *item pointer in the peek and pop functions as an insightful way to use the addresses to access. Thank you again, fantastic content!
@PortfolioCourses
@PortfolioCourses Год назад
You're very welcome, I'm glad to hear you were able to follow along and that you enjoyed the content! :-)
@dangeerraaron
@dangeerraaron Год назад
@@PortfolioCourses Whoops, to clarify, this comment was meant for your Stack ADT and operations tutorial!
@PortfolioCourses
@PortfolioCourses Год назад
@@dangeerraaron Oh ok that makes sense. 🙂
@ashenafigodana
@ashenafigodana Год назад
Thank you Sir. Your explanations completely clear all my confusions.
@PortfolioCourses
@PortfolioCourses Год назад
You’re welcome Ashenafi, I’m glad the explanations cleared things up! :-)
@blankspace1959
@blankspace1959 Год назад
lovely video, glad I found this channel
@PortfolioCourses
@PortfolioCourses Год назад
Thank you very much for the kind words, and I'm glad you found the channel too! 🙂
@yigitcoban9823
@yigitcoban9823 Год назад
This is incredible. I can find all answers that ı have thought about C and C++.
@PortfolioCourses
@PortfolioCourses Год назад
That's excellent to hear Yiğit! :-)
@dorukgencel3997
@dorukgencel3997 Год назад
Your guides rock!
@PortfolioCourses
@PortfolioCourses Год назад
I’m glad you enjoy them Doruk! :-)
@alvarobarboza5730
@alvarobarboza5730 Год назад
another very illustrative !! thank you
@PortfolioCourses
@PortfolioCourses Год назад
You’re welcome Alvaro! :-)
@nicorepetto5781
@nicorepetto5781 Год назад
Time stamps: intro: 0:00 Stack vs Heap: 0:47 malloc: 5:08 Memory leaks/Manual memory management: 12:22 calloc: 18:09 Memory management: 29:18
@theopancini9935
@theopancini9935 6 месяцев назад
cliff-hanger
@kazikmajster5650
@kazikmajster5650 7 месяцев назад
Man, this is actually entertaining!
@PortfolioCourses
@PortfolioCourses 7 месяцев назад
I’m glad you enjoyed it! :-)
@batozorange
@batozorange 2 года назад
Very helpful video, thank you!
@PortfolioCourses
@PortfolioCourses 2 года назад
You're welcome! 😀
@gormarduck1658
@gormarduck1658 Месяц назад
awesome tutorial
@geoafrikana
@geoafrikana Год назад
Splendid explanation. Thanks.
@PortfolioCourses
@PortfolioCourses Год назад
You're welcome, I'm glad you enjoyed it! :-)
@mh7369
@mh7369 Год назад
Excellent video, very helpful, thankyou
@PortfolioCourses
@PortfolioCourses Год назад
You’re very welcome! :-) I’m really glad to hear you enjoyed the video.
@powergladius
@powergladius Год назад
Great video, thank you!
@PortfolioCourses
@PortfolioCourses Год назад
You're welcome! 🙂
@D_Ladybug
@D_Ladybug 2 года назад
You're an awesome tutor! I look forward to when you'll do a video that shows how we can save user's input into a malloc created array!
@PortfolioCourses
@PortfolioCourses 2 года назад
Thank you Olamide! :-) Once you’ve allocated space for the array with malloc filling it with user input is the same as a regular array (“on the stack”), this video might help you with that: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5nyMb7hJ7Xs.html
@D_Ladybug
@D_Ladybug 2 года назад
@@PortfolioCourses Thank you for responding. I feel so honored. I'll try it and get back to you
@PortfolioCourses
@PortfolioCourses 2 года назад
@@D_Ladybug You're welcome. And cool sounds good! 🙂
@manobrodeful
@manobrodeful 2 года назад
#include #include int main () { int i, n; int *a; printf("Number of elements to be entered:"); scanf("%d",&n); a = (int*)calloc(n, sizeof(int)); printf("Enter %d numbers: ",n); for( i=0 ; i < n ; i++ ) { scanf("%d",&a[i]); } printf("The numbers entered are: "); for( i=0 ; i < n ; i++ ) { printf("%d ",a[i]); } free( a ); return(0); }
@kiptooharon9438
@kiptooharon9438 Год назад
amazing very clear
@cscor
@cscor 11 месяцев назад
Thank you very much,good sample programs
@PortfolioCourses
@PortfolioCourses 11 месяцев назад
You're very welcome, I'm glad you enjoyed the sample programs! :-)
@ionguzun3952
@ionguzun3952 2 года назад
so helpful...thanks
@PortfolioCourses
@PortfolioCourses 2 года назад
You're welcome! :-)
@cleightthejw2202
@cleightthejw2202 Год назад
@Host The 'realloc' does apply to 'calloc' as well, correct? I'm pretty sure it does but it wasn't said and I don't want to assume I'm understanding it properly
@dhudach
@dhudach 4 месяца назад
Your videos are very clear and educational. This one is particularly interesting. I've coded in numerous languages including C, master of none. I don't even consider myself an expert in any. But I can be proficient. That aside, I found interesting the section where you save the pointer to the allocated memory into the save variable, free(a) then can still access the data in that memory location. For some reason, I thought or read or heard that kernels prevent access to memory not owned by the program. I guess this is not the case. Can the C program change the value once it's been freed? So does that mean that a C program can effectively step through the entire RAM to inspect and/or change the values?
@philipphortnagl2486
@philipphortnagl2486 Год назад
great content
@PortfolioCourses
@PortfolioCourses Год назад
Thank you very much Philipp! :-)
@Brad_Script
@Brad_Script Месяц назад
heap and stack are not the only memories in C, there's also static memory
@anonymousbelgique7331
@anonymousbelgique7331 Год назад
very good informations thank you sir
@PortfolioCourses
@PortfolioCourses Год назад
You're very welcome! :-D
@love15.01
@love15.01 2 года назад
thank you so much! спасибо
@PortfolioCourses
@PortfolioCourses 2 года назад
You’re welcome! :-)
@ishimwechris3978
@ishimwechris3978 2 года назад
good explanation
@PortfolioCourses
@PortfolioCourses 2 года назад
Thank you Ishimwe, I'm glad to hear you enjoyed it! :-D
@Emanuel-oz1kw
@Emanuel-oz1kw Год назад
Thank you Kevin, thanks
@PortfolioCourses
@PortfolioCourses Год назад
You're welcome Emanuel! :-)
@muhammadaushafalfarras2485
@muhammadaushafalfarras2485 Год назад
Thank you for the informative video! After trying out the code, I'm a bit confused with the output of the *save pointer because from save [ 0 ] to save [ 3 ], it prints out random numbers and not 5, 4, 3, and 2 as expected, while the rest are just fine. Is this because of my own device or compiler? Thank you
@PortfolioCourses
@PortfolioCourses Год назад
I'm not sure Muhammad. I think you should get the same result. The original code is available here: github.com/portfoliocourses/c-example-code/blob/main/dynamicmem.c. That said, while free() is not required to alter the free'd memory (e.g. setting all the memory to zeros or random data), I don't believe there is anything stopping the compiler/OS/etc from doing this either. So if your using the exact same code and getting a different result, it may be due to the compiler/OS. :-)
@muhammadaushafalfarras2485
@muhammadaushafalfarras2485 Год назад
@@PortfolioCourses Thank you! The os may have an effect on the result
@beyzayuksel41
@beyzayuksel41 Год назад
@@muhammadaushafalfarras2485 hi! I got the exact same problem. [0]to [3] gets random numbers or 0's and after [3] it gave me the correct answers. Did you able to solve the problem?
@nathankong8732
@nathankong8732 Год назад
Hi, just here to clear things up about realloc. Realloc is essentially copying an old dynamic array and pasting it into a newly allocated dynamic array with a new size? Is the memory in the old dynamic array free up when realloc call? Thanks !
@PortfolioCourses
@PortfolioCourses Год назад
Great question Nathan! :-) And yes, that's the idea. realloc() doesn't always need to copy the old dynamic array to a new location though, it will do that if it can enlarge the exist block of memory at the existing location in memory. If it does need to move the block of memory to a new location, it will copy the data, and it will free the 'old' area of memory for use again. Interestingly though, it may not CLEAR this block of memory, so whatever was there before, like passwords for example, will remain there. You might find these videos interesting: realloc basics: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-vr7qCQLrUt8.html realloc security vulnerability: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-_Ns0CWEoRio.html handle realloc failure safely: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-skqCnhhA0ZY.html
@six7929
@six7929 Год назад
super helpful tysm..
@PortfolioCourses
@PortfolioCourses Год назад
You're very welcome! :-)
@arthur_p_dent4282
@arthur_p_dent4282 Год назад
Is there a way to specify the amount of memory you want the whole program to occupy? How does the computer decide how much memory to reserve for the instructions/heap/stack together?
@PortfolioCourses
@PortfolioCourses Год назад
That's a good question Arthur and to an extent the answer is that "it depends on the compiler". :-) Often how exactly a program compiles or is setup to execute isn't something that's part of the language definition, so it's left up to the compiler makers to decide. It can also vary from one platform (OS, hardware, etc) to the next too. So while it's a good question, I'm not sure I can provide a great answer. I think learning about compiler and OS design would help to answer these questions though.
@mikehibbett3301
@mikehibbett3301 4 месяца назад
I've always been curious about how malloc deals with new/free allocations of different sizes over time. What does the memory look like over time?
@PortfolioCourses
@PortfolioCourses 4 месяца назад
I think some of that depends on the OS / architecture. But memory can definitely become "fragmented" with lots of gaps and whatnot, depending on what you're doing.
@markjanzer6189
@markjanzer6189 7 месяцев назад
Thanks!
@PortfolioCourses
@PortfolioCourses 7 месяцев назад
Wow thank you very much! :-)
@trivial1344
@trivial1344 11 месяцев назад
At 9:36, do we not need to typecast (int *) into malloc since it returns a void pointer? Or is it just considered good practice/readability
@PortfolioCourses
@PortfolioCourses 11 месяцев назад
Great question! :-) Yes, we don't need the typecast in C because malloc returns a void pointer. In C++ we do use the typecast: stackoverflow.com/a/3477952.
@trivial1344
@trivial1344 11 месяцев назад
@@PortfolioCourses Ohh thanks!! That part had me confused since C++ does int* arr = new int[n]. Love your videos by the way, trying to learn C before college classes start!!!
@marbles5590
@marbles5590 2 года назад
Is it necessary to typecast like: int *a = (int*) malloc (sizeof(int) * 10) Because when I didn't include (int*) like in your code, it returns an error.
@PortfolioCourses
@PortfolioCourses 2 года назад
Great question! 🙂 In C it is not necessary to typecast, but in C++ it is necessary. If you are using a C++ compiler, that might be the reason you get an error.
@marbles5590
@marbles5590 2 года назад
@@PortfolioCourses okay thank you so much!
@PortfolioCourses
@PortfolioCourses 2 года назад
@@marbles5590 You're welcome Shannen! 😀
@MrBolcetik
@MrBolcetik Год назад
Thanks for this awesome video . I am trying to understand the things and I have came up with this question: Can you explain what is the difference between int a[10]; vs. int *a = malloc(sizeof(int) * 10); Thanks a lot.
@PortfolioCourses
@PortfolioCourses Год назад
You're welcome! :-) The short answer is that the first one is declaring an array on the stack, the second declares a pointer variable called 'a' that will "point to an int". What this means is that it will store the memory address of an int. The malloc() function will allocate enough bytes to store 10 int values, i.e. it will go out and get block of memory large enough to store 10 ints. It returns the memory address of this block of memory, and that gets stored into the variable 'a'. We call this a "dynamically allocated array" and it gets stored in a different place in memory than the stack called "the heap". Learning more about pointers can help to learn about dynamic memory allocation: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-2GDiXG5RfNE.html.
@MrBolcetik
@MrBolcetik Год назад
@@PortfolioCourses So many thanks to you, great teacher :) You are my most favorite teacher in youtube on my journey of becoming software engineer. Thanks a lot for everything
@PortfolioCourses
@PortfolioCourses Год назад
You're welcome! :-) And thank you so much for sharing such kind feedback, that means a lot to me!
@SketchupGuru
@SketchupGuru Год назад
Which programming language has pointers and object oriented programming ? Java doesn't have pointers but is a oop language
@PortfolioCourses
@PortfolioCourses Год назад
C++ has pointers and OOP. :-)
@AnalogDude_
@AnalogDude_ 4 месяца назад
Java needs an interpreter, it doesn't run natively.
@SketchupGuru
@SketchupGuru Год назад
So is airplane systems built with the c programming language? And also NASA systems? Also is assembly language much faster than c since it talks directly with the machine? Thanks.. very useful video
@PortfolioCourses
@PortfolioCourses Год назад
I'm not sure what languages those systems are built with. It wouldn't surprise me if they use something "safer" than C, but I don't know. Assembly can be faster than C, but it can also be slower because compilers can be "smarter" about optimizing code execution than programmers sometimes. :-)
@IrohaNatsumeMyBeloved
@IrohaNatsumeMyBeloved 10 месяцев назад
Thanks
@PortfolioCourses
@PortfolioCourses 10 месяцев назад
You’re welcome! :-)
@ApoloOfficial30
@ApoloOfficial30 Год назад
Hello, I would like to ask you if it's also important to NULL a after free-ing int. If it is or not, could you give me some explenation? Thank you so much for your response
@ApoloOfficial30
@ApoloOfficial30 Год назад
Like we it's not reasonable to use it in calloc because this function makes us sure that it is already clear.. but otoh there are some reasons to use it in malloc? I want to make sure that I understand that :)
@PortfolioCourses
@PortfolioCourses Год назад
Hi Adam, whether setting a pointer to NULL is a good practice or not is something people argue about a bit: stackoverflow.com/questions/1025589/setting-variable-to-null-after-free. :-) I would say that it's a good defensive practice to ensure that other parts of the program can check that the pointer is NULL (i.e. not being used to point to memory at that moment), but it may not really solve the problem it's trying to solve. People generally set the pointer to NULL after free to prevent trying to free the memory twice, but that usually occurs when we have multiple pointers to the same position in memory (e.g. by copying a pointer value to another variable) and then we try to free it two times using two different variables that store that address.
@PortfolioCourses
@PortfolioCourses Год назад
If you want to learn about malloc vs calloc this video may help: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-SKBnxCq3HvM.html. :-)
@qwwrt8596
@qwwrt8596 11 месяцев назад
how can i make my visual studio look like yours? btw thanks for the video, i learnt a lot more from this video alone than my college.
@PortfolioCourses
@PortfolioCourses 11 месяцев назад
Just so the video is focused on code, I go to the view menu at the top, and then the appearance submenu, and then I turn off all the different panels. I make the font bigger, though exactly how big depends on the video, that can be done by searching for 'font' underneath settings. And I use Terminal on MacOS, I just have the terminal next to Visual Studio Code on the right. :-) And I'm very glad to hear this video helped you out!
@danielszilagyi9658
@danielszilagyi9658 6 месяцев назад
Interestingly, when I tried the infinite malloc part, it didn't "crash". First the browser window went black. The the whole screen. Apparently Win10 happily lets you steal memory space from running processes.
@rusi6219
@rusi6219 5 месяцев назад
It's a feature for glowies to install malware on your devices
@ChrisOffner
@ChrisOffner Год назад
It's unclear to me why on slide 4 (~2:45) in the stack table we have *c = 8* and *d = 9* when *myfunction* gets called with *a* and *b,* which are 4 and 7, respectively. Shouldn't we have *c = 4* and *d = 7* there?
@0xRAND0M
@0xRAND0M Год назад
No because c,d are variables which are supposed to store the numbers given as arguments when the function is called.
@ChrisOffner
@ChrisOffner Год назад
​@@0xRAND0M Yeah, and the numbers given as arguments when the function *myfunction* is called in *main* are 4 and 7 respectively.
@tsunningwah3471
@tsunningwah3471 4 месяца назад
good
@bougsqf4462
@bougsqf4462 2 года назад
cool man
@PortfolioCourses
@PortfolioCourses 2 года назад
Thank you! :-)
@nathanassefa8787
@nathanassefa8787 Год назад
sir would you please make a video how to use the ide you are using. It is really nice editor. Just make a small video how to use it in windows. Thanks
@PortfolioCourses
@PortfolioCourses Год назад
Great question Nathan! In this video I am using Visual Studio Code. I have disabled some of the standard windows though that allow you to select different files, because in the videos I only want to focus on a single code file (most of the time anyways). The terminal is the other program I am using... the equivalent program on windows would be the command-line (though there are more sophisticated Windows terminals/shells, such as power shell). Maybe one day I can make a video on setting up exactly this 'environment' on Windows and/or a Mac. :-)
@amkhrjee
@amkhrjee Год назад
At 2:04 - Minor correction(maybe): We are essentially passing the parameters a and b to the function. So, c should be equal to a and so is the case for d and b.
@PortfolioCourses
@PortfolioCourses Год назад
That's true, the illustration on the left was more about showing the idea of "the stack". 🙂
@souradeepbanerjee869
@souradeepbanerjee869 4 месяца назад
19:55
@tsunningwah3471
@tsunningwah3471 4 месяца назад
盧卡斯出現尼可拉斯尼可拉斯尼可拉斯內搭褲了
@MoatazBellahezzait
@MoatazBellahezzait 6 месяцев назад
my computer crashed after running that memory loop lol
@joseluizdurigon8893
@joseluizdurigon8893 Год назад
17:15, didn't crashed the program but jammed the whole computer hahahahahaahahaha. Scary
@PortfolioCourses
@PortfolioCourses Год назад
Hahaha 🙂
@AdmiralIbra
@AdmiralIbra Год назад
you can't save data of ''a'' in ''save'' . ''a'' and ''save'' point to the same block of memory ,after you freed "a" , "save" will point to same block of garbage value that "a" point to . doesn't make sense you will get different data from "save" .
@PortfolioCourses
@PortfolioCourses Год назад
I don’t understand your comment, are you just repeating what’s discussed in the video? Or do you have a question? Because in the video I say multiple times that save is storing the same memory address as a. And yes, we don’t get different data from save or a because they are pointing to the same thing. :-)
@AdmiralIbra
@AdmiralIbra Год назад
​@@PortfolioCourses sorry my mistake , I just get confused when I copied this program on my pc i din't get same output, I got some garbage data, not the same as you .
@PortfolioCourses
@PortfolioCourses Год назад
Oh OK I see, thank you for the update I was curious. :-)
@MrOboema
@MrOboema 4 месяца назад
"With great power comes great responsibility." - The bible, right? No, dude. Star Trek. Wrath of Kahn.
@tsunningwah3471
@tsunningwah3471 4 месяца назад
zhin
@platonymous
@platonymous 7 месяцев назад
lol warning running it caused my computer to crash
@PortfolioCourses
@PortfolioCourses 7 месяцев назад
The code in the video will not cause your computer to crash. :-)
@platonymous
@platonymous 7 месяцев назад
@@PortfolioCourses I swear my screen completely went black from doing it on vs code. I did the 10000000 though. Only thing I could do was reset my pc.
@tsunningwah3471
@tsunningwah3471 4 месяца назад
n n n n n n n n n n
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