Structure Padding in C

[@ahamd19]

speachless!! you are soooo goood in explainging. thanks a lot

[@koperaljali3253]

Yes agree.

[@John-sl5zz]

your style of pedagogy has helped me in overcoming phobia of coding. the sort of knowledge you are imparting is enriching our lives. thanx a ton & we look forward to having more such amazing content. kudos to you.

[@devugoel8698]

This was the best. Saw many tutorials, but understood the concept here in one go. I rarely comment on videos, but really had to appreciate you here. Thanks man!

[@عليكيلاني-ي8د]

I couldn't agree with you more , It's awesome how he explained it.

[@WistrelChianti]

Brilliant! I particularly liked the repetition when driving home a particularly important point. Superb work (and exactly what I was looking for - was searching for a good detailed explanation on structure storage in memory).

[@manazirahsan1351]

Tnx

[@andresvallelisboa5511]

Thank you very much! I understood it. I Love the format you chose for the video, a black background, a representation of the memory bytes and everything was explained in a very direct and simple way.

[@manazirahsan1351]

Ok

[@anshhmehta]

Perfect video to understand the importance of padding and its uses.

[@dono42]

Padding is not defined in the C (or C++) standard. This behavior depends on the compiler. It can also be configured too. For example, VC++ has the /Zp and #pragma pack options while GCC has -fpack-struct option.

[@manoharbompella418]

Explained very detailed, Cleared every doubt. Thank you

[@sunilkumarreddy6537]

Sir it is a good class for me. Thank you sir,upto now I didn't no the background allocation of memory now I got clarified. SIR ONE MORE THING, I WANT TO sll,dll,cll,sporting techniques tree's,graphs,bss. Pls... upload sir, one of ur student, thank you sir.

[@manuelconte2127]

It is a good habit to put first the biggest type in ascending order to help compilator !

[@michaelhernandez2075]

trying to read how this works is way harder than having pictures and someone explaining. Thank you.

[@beeyou6220]

I m having 8 yrs of experience. Noone Clarified the doubt lk u..thank you..expecting more content from you

[@rakesh231rakesh]

😱

[@adeshgaikwad2192]

Thank you sir for clearing the concept in such an easy way...

[@andistheinforitbutso7513]

Awesome work 👏 Lesson: we should be careful while arranging the srruct variables for better memory utilisation

[@pnuema1.618]

Padding also becomes a portability issue when code is written on a system with different architecture then the architecture it is being run on. If you already knew this then my apologies. I just feel like understanding padding has more to do with writing portable code.

[@TechnoVisionTV]

Such an amazing explanation! You made it so simple to understand, thank you :)

[@sujitsatpute3741]

You are explaining 💯 times better than my college professor......

[@SJ_46]

1000 bro

[@ArjanvanVught]

Missing to explain __attribute__((packed)) with unaligned memory access which is possible (with ARM).

[@ivanleon6164]

#pragma pack(1)

[@nishantraj5020]

you make every concept so easyyyyyyyyy.

[@khoahuynh6884]

It is always the Indian sensei that makes me understand.

[@mcbotface]

Thank you sir. Keep posting more on stacks, queues, linked lists

[@santanacasas1]

Excellent explanation, thanks for your dedicated time in creating these videos. Regards from Mexico.

[@paschikshehu7988]

1:15 not necessarily wrong, just that 1-packing is not efficient

[@05_abhisheksharma13]

Amazing initiative by neso academy

[@ronnieahabwomugisha5283]

its has been clear. thanks Sir

[@priyaj9908]

Very useful video...Thank you sir.please try to put more videos in advanced c topics..

[@rajmishra6769]

Thanks for the wonderful explanation.

[@あまね-y6t]

really easy to understand for me. thanks a lot！！

[@vijaykounsalye]

just awesome bro you have explained very well

[@y_red_gold_a4280]

Best explanation of the concept. Thank you so much.

[@mikestock1848]

Awesome explanation, thanks for sharing

[@dhruvsakariya3129]

perfect example of 32byte and 64 byte difference thank you very much sir

[@adithyay328]

Good, clear explanation!

[@pnuema1.618]

You are one of my favorite sources for c programming concepts. I know that if you have a video on the subject then I will be able to understand that concept. Thank you!

[@manazirahsan1351]

Ok

[@mdkamrankhan4032]

Great explanation Sir..

[@leepakshiyadav1643]

crystal clear explanation, thanks a lot :)

[@somuseth]

4:40 Sir, does it mean that total of 3 cyles are required to access the 3 variables???

[@kumard-n9m]

Yes

[@pranavkshirsagar146]

Barney Stinson was their... I got so happy after seeing him😆😆

[@VivekYadav-ds8oz]

Why is the compiler not allowed to rearrange member variables? If there's a consistent rule for this, then even external libraries will not face any ambiguity. That way, int variable could've been placed in front, and no wastage will be required and all 3 can be accessed in one CPU cycle.

[@excite236]

Have you tried enabling optimizations with your compiler?

[@premithagoni8634]

Awesome Explanation sir,Thank you

[@Aabara_ka_dabara]

something unique and new things I have learned💕💕

[@QuratulainAzhar]

Amazing 🤩

[@jishankhan6686]

You are really great. Plzz. Give a practical example nd make us clear how a software execute. Suppose i have one software on my mobile then how this software will be executed. Plz give us practical example from first to last.

[@rakurame6990]

Good explanation on structure padding

[@multivalfran]

Excellent video my friend

[@rohiths-k2d]

excellent lecture i have ever seen

[@vishnu5466]

Very Interesting!...

[@mudassar2012]

very helpful video.....so good explanation

[@RozgarBharatIT]

Great Explanation!!

[@amandarash135]

Best explanation

[@umairalvi7382]

Considering the processor is of 32-bit Void main () { char a; } then in the memory for the variable a, only 1 byte will be allocated, then how the processor will request this memory using word...without padding?

[@bharathiapps8230]

The processor would read 4 bytes(from the address of variable char a, it will use only the first byte ), a 32 bit processor always reads 4 bytes(memory is 4 bytes aligned).

[@nileshpokale862]

Excellent Explanation. All cleared

[@donythomas7]

Excellent explanation 👍

[@sohitgore2924]

To handle the case where the memory words are in different memory pages the processor must either verify that both pages are present before executing the instruction or be able to handle a TLB miss or a page fault on any memory access during the instruction execution. Source - Wikipedia

[@avronilbanerjee5302]

excellent explanation

[@kitanowitsch]

For example, with ARM architecture (it's 8bit addressable and 32 bit accessible) engineers and programmers are encouraged to use 32 bit values all the time, so software will run faster and more secure. If memory space is critical then optimization is needed.

[@rakesh231rakesh]

It is all about time and space.

[@gamerplayer94830]

What does addressable and accessable mean? and what is the difference could you please tell? couldnt find or understand from anywhere

[@kitanowitsch]

@@gamerplayer94830 When you write and when you read from the memory, respectively. Data is written by 8 bits into the memory and read by 32 bits. So if your 8 bit data is in 4th memory part of 32bit location, it will take 4 tries to access that particular byte. That's why it is important when you declare structs and any other type of data. More speed and more secure.

[@gamerplayer94830]

@@kitanowitsch thank you very much, i understood! have a nice day

[@kunalsoni7681]

wow great one presentation sir..

[@revan7600]

Very nice explanation thank you

[@shreyasingh222]

Thank you so much for detailed explanation.....

[@chandumadhumanthi9983]

Excellent👍

[@haripriyaraja1890]

Nice clarification 😍

[@aashishmalhotra]

I'm wondering why bloody YT algo doesn't recommend your channel in first year.

[@Siva-fl1sq]

Same feeling..

[@Vishall00018]

Also*

[@kryptoniangaming6082]

Maybe they haven't done the right SEO

[@elchurisrivarna]

Same

[@harshalgarg1149]

Great explanation.

[@JohnDoe-kj2cs]

Silky smooth!

[@garapatianushadevi3427]

Very good, just loved it

[@ahmedsiraj2758]

when declaring 3 char, it should give 4 as output, why giving 3

[@jayaprakashthokala640]

Word size is nothing but highest size of a data type used...

[@anandg4018]

because 3 char are taking 3 bytes of size within the word, and word is actually 4 bytes long thats why it is showing 4 bytes as output

[@ImtiazAhmedRatul]

The reason behind is is that all 3 chars can be accessed using 1 CPU cycle. In other words, for CPU to access char 1 will only take 1 cycle, char 2 will take 1 cycle and char 3 will take 1 cycle. Padding is introduced to save CPU cycles. Since there is no way to get fewer cycles than 1, the compiler doesn't introduce any padding. I understand your confusion. If the CPU is accessing 1 word (4 bytes) at a time, the struct should be char (1 byte + 3 padding) x 3 = 12 bytes in size. What word size the machine will use depends on the type of data it is trying to access. So if it's trying to access a char, it is using word size == 1byte. For int, it will use 4 bytes. When it sees a structure that has both, it will use the highest size (int == 4 in the video's case). In your case, it's using 1 byte for word size.

[@0mer870]

@@ImtiazAhmedRatul It seems you misunderstood his logic. He didn't say it should allocate 12 bytes but 4 which is the word size for a 32 bit processor. And since the instructor said that the processor reads one word at a time and not 1 byte, you'd except it to be always so even if it was just a char it should get allocated 4 bytes as in "1 word at a time". Therefore I think that padding applies only when the size of the variable exceeds the size of a word.

[@lawalayodeji4044]

The null character \0 is 1 byte. It is always at the end of all char or int.

[@Jose_T131]

Very well explained, thank you sir

[@KrupaPrarthana]

Wonderful ❤

[@somasekhardakala2630]

very nice explained....thank you sir 🤝.....

[@aps_269]

Amazing, 😍😍

[@093raselrahman4]

Nothing to say ! Very easy explanation.

[@shauryakumar2229]

Very helpful thanku

[@mamtaCoder]

Thank you sir...😃😇

[@Cat_Sterling]

That was just great! I was wondering about that for so long! But what is a "word" in computer architecture?

[@zidanegimiga8180]

A word must be 4 or 8 bytes long, depending on the computer architecture I guess.

[@nikhilwagh1728]

Great video

[@liangzhang1722]

Life saving! Ty

[@bharatbs7141]

Very Helpfull...Thank You :)

[@fidalgoverde]

Excellent job

[@kirankumarkakileti2811]

Awsome xplanation😍

[@47-6F-64]

Amazing

[@yemreekinci]

Adamsın kral çok güzel anlattın.

[@ashwanirajput9141]

If we declear one more "char" var outside of struct. Then memory allocation for that var is where. 1. Just after var C " 10th place ". 2. 13th place.

[@chintanchatterjee9477]

Respected Sir, I have a doubt in one program of this topic. #include struct abc{ float a; double b; } var; int main() { printf(“%d”, sizeof(var)); return 0; } In 32-bit architecture, the output of the above code should be 12 if float size is 4 B and double size is 8 B. But in online compilers like onlinegdb, programiz, etc., the output of this particular code is 16. What is the reason? I am not getting it. Thanks and Regards. Chintan

[@sushaanthsureshkumar]

Ah you kind of got it wrong, It should be 16 bytes. In Sir's example int was the largest size taking value i.e. 4 bytes, (Alignment value) so have 2 fields char and char then having int will have a total size of 8 bytes. In your case, the largest is double which is 8 bytes. (Alignment value) You have float at first and then double meaning 8*2 = 16 bytes are reserved for your struct and its not 12 bytes. This C way of writing is also used Go. I'm not sure with C++ probably it too has this behavior. Happy Coding @chintanchatterjee9477

[@gurlinkanaveenkumar7209]

Tqu sir.

[@FraPiz]

wow, my mind is blown

[@winxkin6056]

it is very helpful

[@tanmayghosh8311]

never thought we can optimize our code using this methods

[@RezaulKarim-cq5ft]

amazing!

[@anjani_tiwari]

Dhanyavaad🙏

[@yahyaaouledamer1466]

amazing thanks so much

[@krishnakumar-kh5vo]

well explained

[@botelhocpp]

I was thinking... Sure, the processor can only access a word at a time. But wouldn't it make sense to, like, displace the address of the struct a bit to access the integer? Like, in the first example... Rather than padd the first word, wouldn't be better to just add 2 to the address and access the integer right away?? Or this operation would cost too much clock-wise everytime?

[@andyprem]

excellent excellent explanation ..I was having an issue wstructure memebers being read incorrectly and I was suspecting this padding issue. and I was wondering how to explain this to the team .may be I should link to this vedio .. lol ;)

[@silentcat4292]

Crystal clear

[@okavango5937]

If the CPU accesses the addresses only in "word" sizes, then why is 'sizeof(char)' 1? It sould also be 4 (in 32bit) right?

[@RAVITEJAP-ss9rl]

So if we have a variable of char type then it's size would be 4 bytes because that processor can access 4 bytes at a time, but it's not so why? Does this padding concept applicable for only stuctures? Can somebody explain....

[@monarchofaether]

I defined int,char,int in 64-bit computer. I expected sizeof this struct 16 byte but it was 12 byte. 4(int) + 1(char) + 3(blank) + 4(int) = 12byte. Why is it like this ? Shouldn't take also 4 byte ?

[@sushaanthsureshkumar]

#include int64_t i2 = 0x0000444400004444LL; This is how you declare 64 bit integer. regular int is not special, it's 32bit i.e 4 bytes. In your problem the alignment value is 4 so 4*3=12 bytes.

[@karthicknandhakumar264]

Sir, I understand the padding concept..but in 1st case , overall 2 cpu cycles are used with padding and without padding...then what is the use of having padding?

[@abhishekrawat5096]

Please watch video properly , the Instructor have already answered this , in 1st example , suppose you want to access (integer c) , then you will get it only in 1 cycle using "padding" and without padding concept , you have to get the same (integer c) in 2 cycles

[@arshadshaik6554]

@@abhishekrawat5096 yes, correct but in 1 st cycle, along with 2 bytes of int c, already two bytes (char a and char b) are accessed and in second cycle the remaining two bytes of int c are accessed. In this case, Anyway only two cycles are used with padding and also without padding, then what's the use of padding here??

[@debabratamohapatra6638]

@@arshadshaik6554 bro, sir then explained it, suppose u want to access only int c and not char a and b to do so, unnecessary 2 cycles will be wasted which can be done in one cycle using structure paddling. Hp u understood..

[@rishabhjha7565]

@@debabratamohapatra6638 thanks for clearing my doubt

[@RahulRazj]

when declaring a char and then a double variable it should give 4+8=12 as output. But it shows 16. Can someone explain why?

[@kalppariya381]

thats called padding.

[@_sk_beatz_6051]

Your processor is 64 bit architecture may be

[@purubhargava8096]

bhaot hard sirjee

[@KRGAMAING]

thx for the super nice video