Open-source interactive C tutorial in the browser
34 comments
·April 27, 2025herewulf
As great as this looks, I think it should heavily emphasize moving on to using GCC (or maybe LLVM).
I learned C in the mid nineties using a copy of Visual C++ 1.0 that a friend had gotten from his father (and probably he got it from work). It was the only compiler I knew of and once I was ready to move beyond toy programs, I was seriously hampered by the fact that this compiler couldn't produce text mode executables (any call to printf opened its own new window that definitely wasn't cmd.exe) and it couldn't set the graphics mode for blitting pixels. It was heavily oriented around this new fangled MFC thing but I was a teenager so I wanted to program games not business apps or whatever. That meant I wanted text mode or graphics mode.
My high school CS class had Borland C++ and I could set mode 0x13 with that in DOS. But I had no way of obtaining this compiler as a kid. And it probably didn't work on Windows 95 anyway.
Anyways, it wasn't until the early 2000s that I finally learned about GCC, a free as in beer and freedom compiler and the simplicity of it would have been amazing for learning.. If only I had known.
codr7
I stole my copy of Borland C++ from school.
But as mesmerized as I was by C++ at the time, Borland Pascal was a lot more fun to play around with. I remember unsuccessfully trying to wrap my head around the different kinds of pointers, and the humble beginnings of std.
auselen
Probably same years… whenever we got a new computer I was removing OS shipped and installing a previous MS OS. Win3.1? Nah I want DOS, win95 nah… I want 3.1. That’s where my tools were.
Funny thing I still use win10.
lgiordano_notte
funny how much the tools you first get comfortable with shape everything after. even today, setting up a simple clean c environment is way harder than it should be for beginners. tutorials like this help, but eventually pointing people toward gcc or clang early on makes a huge difference long term.
alabhyajindal
I need to brush up on C for my dissertation. How does this compare to Head First C?
I read the first chapter of that book and loved it! Very unlike other books on C which dedicate an entire chapter to `for` loop for instance. How do other programmers even read a book like that? Isn't it tiring to read through how a `for` loop works for the 70th time.
Buttons840
Saw this mentioned in a HN comment and thought it deserved more attention: https://news.ycombinator.com/item?id=34106174
codr7
The more, the merrier, here is another one I've been working on lately:
fuhsnn
> Defined using char, int, short, long or long long
> Note that C does not have a boolean type
`_Bool` and `long long` are both introduced in C99, this is mixed up info.
Edit: probably tailor-made for old MSVC, which didn't support _Bool until VS2013.
PaulRobinson
Ironic that you've drawn the eye to the thing that needs to be front and center of any C tutorial, and also the thing that makes C so tricky to work with.
When somebody says "This program is written in C", my initial thought is "Which C?". There is no one, single C.
I don't write C daily. Heck, I don't write it monthly any more. And so my grey cells are struggling with which versions introduced what, and you've spotted something I would have missed on a first read.
And this is a problem.
Can you list all the undefined behaviours, and which language features came into which version across ANSI, C99, C11, C17 and C23? The last one feels a little brighter in my mind, but I definitely can't, and if I was writing a C tutorial - like many that have been written - I'd probably be explicit about choosing a version and sticking with it, and good luck and godspeed to everything outside that version.
Of course this is one of the reasons learning C is harder than other languages, and why languages like Zig and Odin have a decent chance: ergonomically simpler than Rust, all the power and flexibility, (much) less of the head scratching.
card_zero
Because Zig et al won't have future versions with new features?
PaulRobinson
Sure, but C predates semantic versioning and is rammed with undefined behaviour that a lot of people depend on.
Modern languages - even those that have high levels of C interop like Zig - can (and do) avoid those problems.
jononor
Of course. But they are starting with 40 years less baggage. And can reasonably assume a modern hardware architecture, for example.
larfus
Had a bunch of inconsistencies last time i checked. Not quite comprehensive nor does it have much clarity. I also could hardly see when I disabled my ad block momentarily.
Moral of the story: books are better for learning when it comes to C.
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anovikov
Unbearable with ads all around.
zerr
Surprising that there are still people without ad-blockers. Just install uBlock Origin.
commandersaki
The interactive editor seems to only use a quarter of the screen space and isn't resizable. Quite vexing to use.
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kubb
Good luck to the author with the tutorial. I'm really beginning to accept that despite all of the new languages, like Rust and Zig being available, they won't be able to displace C for the next couple of decades at least. A good programmer will need to learn all the techniques for working with C code safely, efficiently and reliably, with all the inconveniences that implies.
doublerabbit
Most older C developers I've spoken to find Go and Python as a fresh breath of air and refuse to head back.
The younger generations totally sideline C completely.
Myself a non-coder but experienced SysAdmin who can write cool Perl, TCL scripts, C almost feels almost natural when reading it. I just haven't had the time available to dive in.
It could be that I was exposed to it at 14 (2003) but chose perl because MSN/Y!M/AOL messenger bots were the discord bots of today. Still, eager to dive in. Some reason Java too.
dbacar
They host lots of other languages as I see. https://www.learnshell.org/ https://www.learnjavaonline.org/ ...
Skimming through the pages, there is some things that aren't really accurate.
> Integers - whole numbers which can be either positive or negative. Defined using char, int, short, long or long long
char is either signed or unsigned depending on the platform/implementation. Use signed char if you want signed integers.
Telling people who are new to C to define booleans with macros is not a good idea, as they have had a proper implementation since c99.
It also feels weird to treat structs and pointers as advanced topics. They are basically required to be productive in the language.
stdint.h was introduced in c99, not c11.
Explaining bitwise operators as "bitmasks" is also quite weird. Bitmasking is just one of the few things you can do with them.
> In C, functions must be first defined before they are used in the code. They can be either declared first and then implemented later on using a header file or in the beginning of the C file, or they can be implemented in the order they are used (less preferable).
This paragraph reads weird. I haven't found any place where the tutorial mentions how to properly write header files. It might be because of the interactive part, but if that is the case then this tutorial doesn't really teach you how to program in C because the tooling around it is an important part of actually using the language. It is also fairly common to declare functions in order of use. Discouraging that is like telling people they need to use tabs over spaces instead of actually focussing on language semantics.