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It was fun to watch, especially where you made mistakes, thank you for this informative video.

who is here from CS50 ???

Great explanation

@BogdanBudaca i appreciate yr videos, but what set u aside from the others, is the way you explain things, unfortunately in this video, the audio is bad, yes i can see the code, but its missing yr explanation which is the most important part😞

THIS IS WHAT I NEED!! THE PSEUDOCODE IS JUST AWESOME!! THANK YOUUU❤❤

I really appreciate

This was truly helpful. Thank you so much!

Great content man... your page deserves more recognition than it has

I know that it needs to be like this in order to work, but can someone please explain to me the logic behind why does the divisor int needs to be initially declared as 10 and not 1? In my head it makes sense because if the do-while loop divided the ccnumber for the first time, shouldn't it be 10? Why does it already begin with 100 in the first loop. I know that I'm wrong but I can't wrap my head around why it is wrong lol

why don't you just turn your long into a string and use strlen to get the length of your CC number, and then from the math library use pow, to get the first two degits : devide the cc number by 10 to the power of length - 2 ? i wanted to do it this way but i need to use pointers which i don't know how to use properly :')

Thanks so much!!! I just wanted to point out that you can slightly simplify the addition of the 2 digit numbers by just subtracting 9 rather than using %. Adding digits of 14 is 5, 14-9 is also 5. This works for any number 10-19, then you subtract by 18 for numbers 20-29, 27 for 30-39, 36 for 40-49 and so on.

another way: #include <cs50.h> #include<stdio.h> #include<math.h> int main(void) { long n; long cardn; int i; int sum1=0; int sum2=0; int lastn; int d; int count; long power; // request the card numner cardn= get_long("What is the card number? " ); printf(" "); n=cardn; while(cardn<10) { cardn=get_long("What is the card number? "); } //Do addition of every other digit starting from the last digit n=cardn; do { lastn=n%10; sum1=sum1+lastn; n=n/100; } while(n>0); //Do addition of every other number starting from the number second to last after multiplying by 2 n=cardn/10; sum2=0; while(n>0) { lastn=n%10; d=lastn*2; if (d>9) { sum2=sum2+d%10+d/10; } else { sum2=sum2+d; } n=n/100; } int f=sum1+sum2; printf("the last digit in the sum is %i ",f); //know the number of digits n=cardn; for (count=0; n>=1; count++) { n=n/10; } printf("Total number of digits %i ", count); power=count-2; //just to know it is working printf("power is %li ", power); //know the first two digits//know invalid card n=cardn; power=count-2; long divisor=pow(10,power); printf("the divisor is %li ",divisor); printf("the remainder after dividing by 10 is %i ",f%10); if(f%10==0) { if (count==15 && (n/divisor==34||n/divisor==37)) { printf("AMEX "); } else if(count==16 && (n/divisor>50 && n/divisor<56)) { printf("MASTERCARD"); } else if((count==13 || count==16 )&& n/divisor/10==4) { printf("VISA "); } else { printf("UNKNOWN "); } } else { printf("INVALID "); } }

Hello, thanks for the video for starters, could i ask you something tho. Before i watched your video i was getting +2 in some of the testing texts of cs50, i had it a little different than you: instead of creating a variable grade an then round it with the index, i had round ( L - S - 15.8). Would you know why that wasnt working ?, it shouldnt it be the same ?

Really good explanation man, keep it up : -)

Great Video. I was initially getting a floating point exception error. I Had to change the divisor to a float data type, initialise it to 1 and count to minus 1, and all problems were solved. (c++)

Hello everybody, just for future references: While making the cs50 Algorithms problem set, the system showed me an error. This is because the tabulate function is not completely right. I changed the i < candidate_count into j < candidate_count. Then everything worked just fine.

Thanks man, became very helpful.

so i can follow up the logic behind your notes 100% , but when it goes to apply it to code , i start getting lost after the do while loop , i am full beginner , will it be okay to skip this problem till i reach better knowledge ? Or it will impact my studies further if i cant solve it and understand the mechanism after the do while loop in my mind ..

Plâng de 2 zile la problema asta😂 Sper că e cea mai grea de la CS50, fiindca altfel îl termin la anul😜 Dacă nu reușesc pana la finalul săptămânii, revin😁

just finished this problem all on my own. first time coding. so fucking proud of myself. your code is way cleaner than mine, but i'm still happy i was able to get everything to work and all the green smiley faces. keep the faith guys. you can do this even if you've never coded before. just don't give up.

ive followed all the steps but for some reason when type my number then press enter it just goes down a line and doesnt say invalid or anything

After watching the highest viewed videos @8:29 this guy is literally the only person on youtube that i watched who explained this section as if you were a student and didn't assume you know every single detail and process. well done and god bless you, i am now subscribed!!!

thank you 🥰

I'm still trying to wrap my head around contract testing. What's different between this with Pact and integration tests with Mock Service Worker?

Hi there, "public class Main { " can result in compiler error, for the purposes of this tutorial, leave out "public" and your code should run.

nice, really helpful

Amazing tutorial, just what I was looking for!❤

Hi Bogdan, thank you for the video. I am having the problem understanding the logic in around 23 min. For loop is quite complicated, why -2 and how is that divisor work ?? thx in advance

Tanks for helping

I need this in python

2:43 second step : I think in doubling must starting with 4 not 1 ??

thank you sir

Muy buena tu forma de explicar,no entiendo como alguien tan genial tiene tan poco reconocimiento,te deseo éxitos y muchas gracias por la explicación :)

Thank you so much you explained really well and detailed 👍🏽

bro do we get fake cc

De la ce vârstă ai început să programezi?

Thank you so much! I was able to complete the task thanks to your initial explanation.

It s pretty nice to see someone experienced does it :D i managged to complate is in 3hour without help Just started cs50

legend

Can you share the report pdf of this

why we use return 1 ????????????

Great👍

I really love the way you explain your logic, and then don't assume it is obvious. I like how you hope we were able to follow along instead. You seem like a genuinely nice guy. Thanks, Bogdan.

Very good explanation 👌..thank u very much ... 🙂

ρгό𝔪σŞｍ

I really appreciate the way you went through the problem. It was by far the easiest video for me to follow and understand the logic. Thank you for sharing it with us.

Thank you this helped me better understand the problem !

Darling, i've walked to Mordor and beyond trying to find something like this! Thank you! this is just what i needed!

please in this part // check validity of the key for (int i = 0; i < strlen(argv[1]); i++) { if (isdigit(argv[1][i])) { valid_key = true; he gives [Error] Initial 'for' loop declarations are only allowed in C99 or C11 mode

Thanks for the good explanation and documentations