Let's write a recursive descent parser in C (Part 1)

[@esmam123]

The fact that you have the diagram on the left side sketching each step is very very helpful. Thank you!

[@alanextar]

the most useful video which I found on the internet, especially for beginners who wants to learn through practice! keep going, man!

[@karthiknandula]

If you're a beginner, definitely watch this. It breaks down the concept of an RDP very well and goes through an actual example so is super useful.

[@trueverdicts685]

Great tutorial! Most people are too brief but you even explain with live illustrations and that's thoughtful! :D

[@mubafaw]

Wow! Brilliant, clean, concise, easy to follow, yet very powerful. Thank you so much. Made my day :)

[@pedriuskii]

Im no begginer, but math has never been my strength. I've been trying to write something like this for two days breaking my head, and you solved it in less than 15 minutes. Haha... Thanks a lot for the help, and for making me realize how bad i am :)

[@eeddeellwweeiiss]

Thank you! It is so clear for me now. Without any tokens and libraries! Just thank you, man!

[@shekharaakula6233]

Awesome video! Great work on skorbut! Have been looking for something like this for sometime, this is great for beginners.

[@xCwieCHRISx]

very nice IDE to visualize the memory. thank you.

[@misterbazzan]

Thanks @Fred Overflow

[@ademyro]

Really nice, thank you very much, helped me a ton!

[@devenderprasad9737]

Thanks for explaining this way.

[@XediXermawan]

Hi, In this parser, the assumption is we already now the general structure of the input ,is not it ? . just wondering how does this parser will be implemented when we don't know the input structure at first

[@ivaylokanyov924]

Man, can you make PART 3 for this calculator?

[@IrwinRodriguez]

Hi Fred, thanks for this example. I'm learning parsing techniques and this video is really helpful. Do you have any course or something?

[@MsOwenMeany]

Why not name the function that parses singular digits parseDigit?

[@5hirtandtieler]

Thanks a ton for this very helpful tutorial! Question though, does skorbut have it's own page where I can find any more info about it? I tried googling it, but seeing that "skorbut" is "scurvy" in Latvian, I was getting a lot of irrelevant pages :P edit: To anyone worried about the file, I've scanned and ran it without any issues (i.e. it's virus free)

[@fredoverflow]

See updated link in the description ;)

[@thomastheilmann581]

kannst du das nochmal auf deutsch machen ?

[@abhishek420oviyt]

Ive gotten bored of the hellow world equivalents of recursion... This was nice for a change

[@Alex-bd6ux]

Great tutorial! Thanks you!

[@Darieee]

Great tutorial !!!

[@IrwinRodriguez]

Hi Fred, I'm using the skorbut application because I'm learning C. I like the syntax highlight control you used in Java, could you tell me how can achieve something like that? I have some syntax to highlight and it would be nice to do it with Java. Thanks!

[@fredoverflow]

What you see in this old video is RSyntaxTextArea. In the meantime, I wrote my own editor and syntax highlighter from scratch. You could study that in 3 other github repositories of mine: freditor, clopad and karel. But I would strongly suggest to use RSyntaxTextArea instead.

[@IrwinRodriguez]

@@fredoverflow thanks for the tip, I'll check it out.

[@AbdSab193]

Thank's for the tutorial !

[@eternalprogrammers8053]

Well, but where are you writing this parser in this video?

[@fredoverflow]

github.com/fredoverflow/skorbut-release

[@eternalprogrammers8053]

Thanks for replying and giving me this link!

[@victorolvera6482]

🤔 I don't this level of coincidence. Soo I will ask. What was the process that made you decide on your thumb nail for this recursive descent series BECAUSE I just finished a video about parsing. And you used the same pic of your thumbnail that I used mid video. My process for picking that image, I think I went to Pexels or RawPixel, I searched out rabbit hole because I was thinking Alice In Wonderland (the video game) and I am felt recursive descent is just going down the rabbit hole. The search results turned up rabbits and holes but also spirals. And I liked the spirals and I ended up choosing with that image. I never saw your video, I doubt you saw mine, I had searched for recursive descent videos but your video never came up. Only today did KZbin recommended your video. A couple of days after I had published it on Odysee. I don't publish on KZbin because I have a personal policy of boycotting Google. Anyways, yes, do you remember the thought process for choosing your thumb nail for this video?

[@fredoverflow]

Honestly can't remember, I haven't touched the thumbnail in years... these days I would probably just search for _stairs_ on stocksnap!

[@Kosake82]

Where can I find part 2?

[@fredoverflow]

I just uploaded part 2 :)

[@nolimangulabnan6101]

i dont get why you put return *x++ instead of *x . please explain. thanks

[@tedremmets8331]

To increment x after return

[@nolimangulabnan6101]

i got it thanks Ted :)

[@IrwinRodriguez]

Hi Fred it's me again, I'm learning this topics because one of the things I want to create is cool stuffs for Visual FoxPro (custom commands, new grammars, and so on...) but the problem is I only know this language and that's too bad because it is a dead language since 2015 (that's why I want to recover some of its syntax). Having said that, what language can you suggest to get a deeper understanding? should I choose a compiled language for a better performance or scripting language will quite good as well? thanks!

[@fredoverflow]

I'm not sure what you're asking. Do you want to write an interpreter/compiler for a simple, real-world language? Then LISP would be my first choice, followed by a small but still useful subset of C. Or do you want to write an interpreter/compiler for Visual FoxPro, and you are asking about the implementation language for that interpreter/compiler? Use whatever language you're most familiar with. A good intro to the world of interpreters/compilers is craftinginterpreters.com

[@IrwinRodriguez]

​@@fredoverflow thanks Fred. Both answers were valid for me. I want to create a simple interpreter for Visual Foxpro but I don't know what inplementation language to use, I think I'll give it a try with Java and see what happens.

[@IrwinRodriguez]

@@fredoverflow Hi Fred, I was reading a little about LISP and It looks like it is a great choice for a compiler/interpreter implementation but should I use LISP itself or Common LISP or may be Schema?

[@fredoverflow]

@@IrwinRodriguez The only LISP dialect I have used in recent years is Clojure. If I were serious about LISP, I would buy a book and use whatever dialect that book discusses. For example, the seminal classic "Structure and Interpretation of Computer Programs" uses Scheme, if I remember correctly.

[@fredoverflow]

@@IrwinRodriguez craftinginterpreters.com starts with Java and later switches to C. You can write interpreters/compilers in pretty much any mainstream language. If you're already familiar with Java, just use Java.

[@SIGMA_BLYAT]

what's the ide you're using?

[@fredoverflow]

There is a link in the video description (between the video and the comments).

[@SIGMA_BLYAT]

@@fredoverflow By the way, I have been enjoying watching you building OSs, Parsers and stuff, thank you for such a great content! I would like to see you building your own programming language :D

[@fredoverflow]

Thanks! Does the world really need yet another C, LISP or ML derivative, though? ;)

[@SIGMA_BLYAT]

@@fredoverflow :D

[@protopet9604]

How do you get a IDE to show the values of the variables like you have on the left side of the screen?

[@fredoverflow]

github.com/fredoverflow/skorbut-release

[@MrMastrsushi]

Why is it bad practice to return values; is it just in the case of parse functions?

[@fredoverflow]

What part of the video are you referring to? Please provide a timestamp or an exact quote.

[@MrMastrsushi]

Fred Overflow 4:36, when return in else

[@fredoverflow]

"I'm not going to return a value, which is very bad practice" means that it is very bad practice NOT to return a value. You should ALWAYS return a value inside non-void functions! In this case, I deliberately exploit the behavior of my IDE to crash the program when I forget to return a value. Real world environments don't provide that luxury, and the function would return some pseudo-random garbage value instead.

[@SO-dl2pv]

Thank you very much

[@ashrafuzzamanshahriar7701]

How can i implement it with any digit number :(

[@fredoverflow]

This is explained in part 2, which I just uploaded :)

[@nmmm2000]

what is this IDE? also OS? also what is the compiler?

[@fredoverflow]

It's a custom IDE written by yours truly: github.com/fredoverflow/skorbut-release The OS in the video is Linux Mint, but the IDE should work on any OS supporting Java 7. No external compiler is required, the IDE uses an internal compiler/interpreter.

[@yousefalghamdi10]

I tried to implement multi digit number but couldn't successescould you give me a good resources or make a tutorial for that proposethank you

[@fredoverflow]

See part 2 :)

[@danstoian7721]

Are you german? You sound german, especially when you say 'digit'

[@teckyify]

Nice, but it doesn't particularly help to deal with the details of an awkward language.

[@aishahhamidon2930]

its too long