How to encrypt messages (Substitution cipher) - C Programming

[@BogdanBudaca]

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[@lpataro]

Usually I solve the exercises by myself then come here to check which path did end up choosing to pursue. Specially when I'm not super satisfied with my own solutions. It always gives me clarity on the logical aspect of things. Cheers from brazil

[@BogdanBudaca]

Thanks Leonardo, cheers

[@sanitarora7554]

After watching your videos, the programs seem so simple and doable! Thanks, man.

[@BogdanBudaca]

Cheers Sanit, glad you liked it

[@maanvijoneja3668]

Love your channel. Pls keep on making videos like these. Pleaseee. They are life saving

[@BogdanBudaca]

Thank you, Maanvi

[@josephsozio7316]

This helped me a ton thank you! I was missing the bit about ASCII code subtraction.

[@BogdanBudaca]

Really glad Joseph, cheers

[@green-coder]

sir you are the best

[@BogdanBudaca]

Cheers Tecno, glad it could shed some light

[@AlexanderFedorOFF]

Thanks for your videos man, I like the way you explaining things.

[@BogdanBudaca]

Glad you liked it

[@yannmapouka8375]

thank you for your explanations !

[@BogdanBudaca]

Cheers Yann

[@matheusrocha8037]

Tanks for helping

[@mawadhsalah1207]

Thank yooooooooooooooooooooooou very much ♥♥

[@MKSundaram]

HI, could you please tell me how can I write sustitution cypher program without fgets?

[@BogdanBudaca]

Hi M K, you mean without getting user input at all, or using an alternative to fgets()? For the former I think then you could just hardcode the text inside the program if you'd want to use it for nothing else; for the latter, I see some results if I run a G search but can't say I've used anything else so far to be familiar with.

[@MKSundaram]

@@BogdanBudaca Thanks

[@naveenthayyil8768]

legend

[@hieunguyentrung8084]

Can you show the code that decrypt the thing you have just encrypted?

[@BogdanBudaca]

Thanks Hieu, might do a video on that then

[@hieunguyentrung8084]

@@BogdanBudaca When? Can be by Sunday 25/10?

[@BogdanBudaca]

Afraid not Hieu, I'm a bit caught up for a few weeks.

[@aloysiuskuon1553]

Hi, would it be possible to explain how does the for loop after line 32 is related to char input [500]? Is char input [500] an array of 500 empty 'slots' that stores the difference between characters of plaintext and 'A' or 'a'? I'm new to this and have been trying to figure out how to implement the code for ciphering specifically. Would really appreciate it if there could be a way to explain what you meant in your code. Thank you.

[@BogdanBudaca]

I've used 'char input[500]' to indeed get an array of characters (letters) with a length of 500, just to be able to store/accommodate the plaintext and have some room for it. Then with the difference we just replace each letter with the one from the key (we deduct 97 or 65 to get the right index because that's from the ASCII codes tables index, but we need only indexes from 0 to 25 in the key). Hope this helps, try playing around with the code, it will make sense

[@aloysiuskuon1553]

@@BogdanBudaca I see... Able to picture it better now. Thank you very much!!

[@maanvijoneja3668]

Please make a video on plurality pleaseeee

[@BogdanBudaca]

Thank you for the idea 🙂

[@yaserthedev2581]

Is this homophonic substitution or polygram substitution?

[@BogdanBudaca]

Hello, hmh I think this is just simple substitution, not entirely sure

[@hexohydraheretic4697]

between lines 32 and 41 is argv incrementing aswell, because its in the for loop. sorry im just not seeing where your substituting the plain text for the key

[@BogdanBudaca]

Hi, are you referring to the loop that changes the input? It doesn't change argv, it just goes to the index in argv based on the ASCII code of the letter being looked at from the input and deducting the respective value for lower or upper case, and then it passes that value to that input index, basically doing the substitution.

[@davidkim2319]

Are you a software engineer taking CS50 for fun?

[@BogdanBudaca]

Yes, I love the solid foundation it offers and I think I lacked many of the things it puts on the table as far as an intro to CS goes. Always good to revisit foundations too, I think. And I also love the teaching manner and the whole fun approach, really glad I have such access.

[@davidkim2319]

​@@BogdanBudaca do you use the things you learned in the more comfortable problems in your day-to-day tasks? In other words, is it worth the time to do the more comfortable problems ?

[@BogdanBudaca]

TLDR: Oh I'd say so, yes. They're super interesting and I think it's a good hands-on, they tie well into the whole package. (I'm pretty sure they wouldn't be a time waste anyway). For me, it's not so much what I learned with the 'more comfortable' problems alone, it's really going through the whole experience. A few things I found helpful overall: - a deeper understanding of what is going on under the hood, things I now kind'a take for granted from my predecessors, for example data structures, algorithms, or even memory management with newer programming languages, or as low as the 0s and 1s - SQL - Python - The final lecture and the Web track were awesome, filled with the HTML/CSS/JS trifecta, and also connecting with Python/Flask and a DB of choice - Yes, the hands-on rocked (- Bonus - even had a look at the now deprecated Android, iOS and Games tracks and they are super interesting too)

[@davidkim2319]

@@BogdanBudaca Sounds awesome. What keyboard do you use?

[@BogdanBudaca]

Oh just some cheap wireless thing, I'm not very picky :)