My personal C coding style as of late 2023

https://nullprogram.com/blog/2023/10/08/

by zdw • 3 years ago

557 438 3 years ago

I disagree about the structs vs out-parameters thing. I’ve found it makes functions that could return an error much harder to compose and leads to a proliferation of types all over the place. In practice almost all functions can fail (assuming you are handling OOM), so having a predictable style of returning errors is more important.

staunton• 3 years ago

assuming you are handling OOM

Which almost noone ever does. It's very hard and almost never has any benefit. At that point you have way different problems than programming style choices...

JonChesterfield3• 3 years ago

Returning option<foo> (or sum<foo, error>) is the right thing but a real pain to write in C. I'm not sure the pattern of `if (thing(...)) goto fail` on every function call is particularly wonderful either, though the Go crowd seem to like it.

Otherwise there's thread_local mylibrary_errno, which might actually be the right thing for within a library, translating it to an enum return on the boundaries.

kamray23• 3 years ago

You'd get normal errno/out param semantics if you had access to semantic struct unpacking. But you don't. Even then, composing optional values in C has always been a bit of a pain. If you're not doing exceptions, your two choices seem to be exceptions and monads in every language, and neither work in C, or would even be compatible with the philosophy that most C programmers have. I guess you could attempt to pull some kind of macro but it only works on simple one-to-the-other calls. C++ optionals, as terrible as C++ is, are certainly more fun to use than

    if(foo(x,y, out1, out2) != WHATEVER_LIBRARY_OK) { ... }

antiquark3• 3 years ago

#define sizeof(x) (size)sizeof(x)

Technically, it's illegal to #define over a language keyword.

chii• 3 years ago

really? then how do you #define things like types like `int` and `char`?

antiquark3• 3 years ago

For example, it would be illegal to do the following:

#define int long

Because you're replacing the int keyword with something else.

The standard says:

17.6.4.3.1 [macro.names] paragraph 2: A translation unit shall not #define or #undef names lexically identical to keywords, to the identifiers listed in Table 3, or to the attribute-tokens described in 7.6.

tom_2• 3 years ago

You don't.

oh_sigh• 3 years ago

Also, `#define countof(a) (sizeof(a) / sizeof(*(a)))` is unsafe since the arg is evaluated twice.

badsectoracula2• 3 years ago

This is a very common macro to get static array lengths and i'm not sure there is any other way to do the same thing (i.e. give a static array, get back the number of items in it) in any other way.

david2ndaccount3• 3 years ago

Arguments to sizeof aren’t actually evaluated (except for variably-modified-types, AKA VLAs, but don’t use those).

f33d5173• 3 years ago

The arg is expanded twice but evaluated zero times, since sizeof gives the size of its argument type without executing anything.

wannacboatmovie• 3 years ago

If you're dead set on doing this, the correct way would be to name the macro in all caps e.g. #define SIZEOF(x) as C is case sensitive. It is somewhat self-documenting to the next guy that SIZEOF() != sizeof().

loeg2• 3 years ago

Any name is fine, as long as it isn't literally "sizeof".

mianos• 3 years ago

Considering '#defines' are done in a textual pre-precessing by the C pre-processor, they don't know much at all about the C language. You can define out int, long, struct or anything.

I have seen many people redefine 'for' and 'while'. These people often argue that it is an improvement.

  cpp
  #define sizeof(x) (size)sizeof(x)
  sizeof(UU)

  # 1 "<stdin>"
  # 1 "<built-in>"
  # 1 "<command-line>"
  # 31 "<command-line>"
  # 1 "/usr/include/stdc-predef.h" 1 3 4
  # 32 "<command-line>" 2
  # 1 "<stdin>"
  (size)sizeof(UU)

orthoxerox• 3 years ago

I have seen many people redefine 'for' and 'while'.

    #define while if

MBCook• 3 years ago

A lot of this makes sense to me.

I’ve started writing a bare metal OS for Arm64. It’s very early but I’ve done some similar things. I’m using pascal strings, I’ve also renamed the types (though I’m using “int8” style, not “i8”).

I quickly decided that I never intend to port real software to it, so I really don’t have to conform to standard C library functions or conventions. That’s given me more freedom to play around. C is old enough to have a lot of baggage from when every byte was precious, even in function names.

It’s nice to get away from that. Much like the contents of this post, that plus other small renamed just ended up feeling like a nice cleanup.

eddd-ddde• 3 years ago

i never thought about that, saving bytes even in symbols

Eggsellence• 3 years ago

I think he is suggesting the opposite - use more verbose names for clarity.

trealira• 3 years ago

Yeah, old C compilers would only look at the first 6 characters of a name, and the rest were insignificant. That's how you get nanrs like "strcpy" and "malloc" instead of something like "string_copy" or "mem_allocate" (I still think "memory_allocate" would be long enough to be annoying to type).

vdqtp3• 3 years ago

I never intend to port real software to it, so I really don’t have to conform to standard C library functions or conventions.

So you're just building it as just a hobby, won’t be big and professional like gnu?

1f60c• 3 years ago

Context: Linus Torvalds' announcement of Linux to comp.os.minix: https://www.cs.cmu.edu/~awb/linux.history.html

ForkMeOnTinder• 3 years ago

To beginners it might seem like “wasting memory” by using a 32-bit boolean

Maybe I'm a beginner then. He lists a few cases where it's not worse than sticking to 8-bit bools, but no cases where it's actually an improvement. It still wastes memory sometimes, e.g. if you have adjacent booleans in a struct, or boolean variables in a function that spill out of registers onto the stack. Sure it's only a few bytes here and there, but why pessimize? What do you gain from using a larger size?

Quekid52• 3 years ago

Computer architecture is optimized for 32+ bit aligned access to most things. The gain is (usually, but not always!) performance.

gavinhoward2• 3 years ago

I'm afraid you are only slightly correct.

Architectures are generally optimized for aligned access (or disallow unaligned access), but what counts as "aligned" is different for each type.

A char type that is used for a bool can be accessed on any byte boundary because the alignment of a char is 1. The alignment of a 32-bit value is 4.

However, architectures are generally more optimized for 32-bit operations in registers. If you're dealing with a char in a register, the compiler will generally treat it as a 32-bit value, clearing the top bits. (This is one of those places where C's UB can bite you.)

However, there are architectures where 32-bit access is optimized.

tedunangst• 3 years ago

What's an example of a function where a boolean variable spills to the stack and the 3 bytes are important?

gavinhoward2• 3 years ago

And to add to that, if you use an actual bool type, sanitizers will warn you if they are ever any value other than false (0) or true (1).

defrost2• 3 years ago

It depends entirely on the architectures | CPUs, that said the obvious case from past experience is numeric processsing jobs where (say) you flow data into "per cycle" structs that lead with some conditionals and fill out with (say) 512 | 1024 | 2048 sample points for that cycle (32 or 64 bit ints or floats) .. the 'meat' of the per cycle job.

My specific bug bear here was a junior who insisted "saving space" by packing the structs and using a single 8 bit byte for the conditionals.

Their 'improved' code ground throughput on intel chips by a factor of 10 or so and generated BUS ERRORs on SPARC RISC architectures.

By packing the header of the structs they misaligned the array of data values such that the intel chips were silently fetching two 32 bit words (say) to get half a word from each to splice together to form a 32 bit data value (that was passed straddling a word boundary) to pipe into the ALU and then do something similar to repack on the other end - SPARC's quite sensibly were throwing a fit at non aligned data.

Point being - sometimes it makes sense to fit data to the architecture and not pack data to "save" space (this is all for throughput piped calculations not long term file storage in any case)

xvedejas2• 3 years ago

This is the use case for `uint_fast8_t` (part of the C99 standard); it should use whatever width of unsigned integer is enough to store a byte, but fastest for the platform. You always know that the type can be serialized as 8 bits, but it might be larger in memory. So long as you don't assume too much about your struct sizes across platforms, it should be a good choice for this. Although, if alignment is an issue, it might be a bit more complicated depending on platform.

comex4• 3 years ago

But if you don't use packed attributes, then the compiler will still add padding as necessary to avoid misalignment, while not wasting space when that's not necessary.

bandrami3• 3 years ago

At one point a loooooong time ago we said "let's give every struct its own page" as a joke but... holy crap, it was so much faster.

eyegor• 3 years ago

Most of the time an easy optimization is to pad fields of your struct to a 32 bit boundary. Almost any compiler will do this for you (look up "struct alignment / padding"). If the compiler is going to do this anyway, might as well use the memory yourself instead of letting it be empty space. If it doesn't happen, you leave performance on the table, so doing this raises the chance that your struct/fields will be aligned.

Nuance is that each field should be at an address divisible by the fields size or wordline size, not some magic 32 constant. The entire struct should also be padded to a multiple of the largest fields size. In practice this usually means 32 bit alignment.

Ref http://www.catb.org/esr/structure-packing/

cshenton• 3 years ago

Really lovely. A lot here reminds me of design in Odin lang. Short integral types, no const, composite returns over out params. Big fan of the approach of designing for a single translation unit and exploiting the optimisations that provides from RVO etc.

im3w1l3• 3 years ago

#define assert(c) while (!(c)) __builtin_unreachable()

This seems like a bad idea, because the whole point of an assert is that something shouldn't happen, but might due to a (future?) bug.

haimez2• 3 years ago

This seems like a bad idea, because the whole point of an assert is that something shouldn't happen, but might due to a (future?) bug.

And so it’s a bad idea because…?

The whole idea is to notice a bug before it ships. Asserts are usually enabled in test and debug builds. So having an assert hit the “unreachable” path should be a good way to notice “hey, you’ve achieved the unexpected” in a bad way. You’re going to need to clarify in more detail why you think that’s a bad thing. I’m guessing because you would prefer this to be a real runtime check in non debug builds?

im3w1l3• 3 years ago

It's undefined behavior if the assert triggers in production. It's too greedy for minor performance benefit at the risk of causing strange issues.

ww520• 3 years ago

This is an excellent writeup. I especially like the string treatment and the fat-pointer struct parameters and return values.

bsder• 3 years ago

signed sizes are the way

Well, I should probably just say "We're done here." and stop reading the rest of the article. "Signed sizes" are an extremely surprising abstraction break that are just asking for disaster.

No const. It serves no practical role in optimization, and I cannot recall an instance where it caught, or would have caught, a mistake.

Should you even be writing C if you haven't hit this? People mix up "in buffers" and "out buffers" all the time. "const" flags this immediately.

Declare all functions static except for entry points. Again, with everything compiled as a single translation unit there’s no reason to do otherwise.

And when you go trying to debug something and get at a variable or function that you can't find because everything is "static", you'll curse the one who wrote the code.

Another change has been preferring structure returns instead of out parameters.

Which is a great way to accidentally return a pointer to your stack and open a big ass security hole. Passing in the output buffers makes clear the ownership semantics.

This guy seems like he mostly writes code for 64-bit systems. The coding advice is ... okay, I guess? Maybe? In that domain?

In a 32-bit embedded domain, some of these guidelines are a good way to get youself into a lot of trouble in a real hurry.

tom_2• 3 years ago

The no-const people will never be satisfied, so just use const as necessary, propagate as required, and ignore them when they complain. If they take it out, put it back in. They'll always get bored first. I've been doing this for 25 years, and I'm still here.

(The static thing might depend on the tooling. I went static-by-default about 15 years ago, around the same time I went full size_t, and I've yet to have a problem with it.)

thefourthchime• 3 years ago

I’ve been her 30 years. I’ve never found much use for const. I value brief simple code that doesn’t rely on things like const to tell people what’s going on.

Codebases have their own conventions and design patterns. If you have that const is a needless formality.

Code should be being simple and clean first, constantly stating things that are obvious 90% of the time isn’t that.

ripe• 3 years ago

signed sizes are an extremely surprising abstraction break that are just asking for disaster.

Bjarne Stroustrup wrote a detailed memo advocating for signed sizes:

https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p14...

josephg4• 3 years ago

Eh, I hard disagree with this memo. He's either dismissing or unaware of the biggest advantage of unsigned types, namely they make invalid state unrepresentible. And essentially all of his criticism of unsigned types is really criticism of the sloppy way old C and C++ compilers let you mix signed and unsigned numbers in math operations.

Modern C/C++ compilers can and will warn you (quite aggressively) if you mix signed and unsigned numbers without thinking about it.

A lot of the examples also seem weird. Eg, he gives a negative example of a function:

    unsigned area(unsigned x, unsigned y) { return x * y; }

In this, he complains that you can still write buggy code:

    area(height1-height2, length1-length2);

He's right - that is potentially buggy, But, that code would be buggy whether the area function took signed or unsigned numbers as input. However, the signed version of this function is still worse imo because it could hide the logic bug for longer. If the area function should always return a positive number, I'd much rather that invalid input results in an area number like 4294967250 than a small negative number.

Similarly, accidentally passing a negative index to a vec is much more dangerous with signed indexes because v[-2] will probably quietly work (but corrupt memory). However, v[4294967294] will segfault on the problematic line of code. That'll be much easier to find & debug.

And a lot of the examples he gives, you'd get nice clear compiler warnings in most modern compilers if you use unsigned integers. You won't get any warnings with signed integers. Your program will just misbehave. And thats much worse. I'd rather an easy to find bug than a hard to find bug any day of the week.

ComputerGuru3• 3 years ago

I might just be a grumpy old dev but a lot of this stuff gets an immediate no from me because it’s so unidiomatic. You have to unlearn the accepted way of doing things and you end up with a codebase that is just so foreign to anyone looking at even a small chunk of it, unless they are committed to really learning to do things your way.

Everyone knows what a uint32_t is when they see it. The cognitive overhead (until it becomes second nature, obviously) just feels like a heavy price to pay in order to save yourself a few characters.

(Some other stuff in the proposed coding style still gets a thumbs up from me, though.)

Pannoniae• 3 years ago

Unpopular opinion: something being unusual does not necessarily mean it is bad. Yes, it will look foreign to random people looking at it, but if someone wants to seriously work with it, it will only take a few days to get familiarised with it. The justification of "cognitive overhead" is, from what I have seen, a shibboleth for rejecting "outsider" code written by someone not conforming to the language standards by claiming it is harder to understand. Personally, I would say that says more about the person's inflexibility and/or OCD, not the writer's style.

I am not saying every style is good (some simply obfuscate things and/or make things overly verbose or unreadable) but rejecting a style solely based on it being "non-idiomatic" is not a good thing.

thetic4• 3 years ago

I don't even think that's a controversial opinion. Breaking convention isn't inherently bad; it has costs, some of which you described. In this case specifically, the novelty is not justified by any significant benefit.

yura• 3 years ago

Well said. This is also something that I don't buy from the criticism towards Lisp. Something along the lines of: "Lisp did not become mainstream because everyone writes their own little language for their project, and so no one can understand other project's code."

pg wrote excellent arguments against this criticism in "On Lisp" § 4.8 Density, which apply just as well to the discussion above:

    “If your code uses a lot of new utilities, some readers may complain that it is hard to understand. People who are not yet very fluent in Lisp will only be used to reading raw Lisp. In fact, they may not be used to the idea of an extensible language at all. When they look at a program which depends heavily on utilities, it may seem to them that the author has, out of pure eccentricity, decided to write the program in some sort of private language.

    [...]

    If people complain that using utilities makes your code hard to read, they probably don’t realize what the code would look like if you hadn’t used them. Bottom-up programming makes what would otherwise be a large program look like a small, simple one. This can give the impression that the program doesn’t do much, and should therefore be easy to read. When inexperienced readers look closer and find that this isn’t so, they react with dismay.”

benreesman• 3 years ago

I want to both be polite to the OP but also agree.

Writing correct C is hard, so I’m not going to knock anyone who found stuff that helps them.

But pound defining shit to things you know via your Hungarian notion? Write some elisp. My Haskell programs don’t actually have Unicode lambda in them.

Pascal strings? Yeah, that’s probably the better call, but why not use C++ or Rust or something where a bunch of geniuses got it right already?

saulpw• 3 years ago

Too many geniuses spoil the soup. We all see many of thousands of recipes and techniques over the course of our careers and it makes sense that each of us are continuously curating the small subset that we reach for in every project. I enjoy seeing the workbenches of other craftsmen, and nothing here looks unfamiliar.

Arthur Whitney however is nuts.

mikewarot2• 3 years ago

Pascal strings? Yeah, that’s probably the better call, but why not use C++ or Rust or something where a bunch of geniuses got it right already?

I'll be diving into C fairly heavy for the first time ever next year. I intend to skip right past pascal strings and implement/use free pascal's AnsiString or UnicodeString, both of which are reference counted, have a length (with no limit) and are guaranteed null terminated. I've stored a gigabyte in them in a few milliseconds. There's no need to allocate or free memory either... it's like freaking magic.

dev_dwarf• 3 years ago

You'll find by looking at their older posts that the author has actually written quite a lot of elisp.

mberning• 3 years ago

To be fair they did say that when contributing to a shared project they follow the prevailing standard.

I don’t see the harm in following this for your own passion projects. You aren’t doing it for the world, you’re doing it for yourself.

ComputerGuru3• 3 years ago

I mean to each their own, but in my own experience, I value being able to easily and reliably copy-and-paste code snippets across projects (and I have a million of them, across several evolutions of my own personal coding styles and conventions) or files without worrying about whether the typedefs are in scope, polluting a namespace with possibly conflicting names or macros, etc.

I also have often found myself publishing “for my own use only” code as open source later and like to keep things understandable to maybe help teach someone something someday.

badsectoracula2• 3 years ago

I might just be a grumpy old dev [...] Everyone knows what a uint32_t is when they see it.

You might not be old enough then :-P many codebases typedef their own int types. See glib (gint, gshort, gint32, etc), SDL (Sint32, Uint32, etc) off the top of my head and there are many that define types like "int32" or "i32" like the linked article.

ComputerGuru3• 3 years ago

I cut my teeth on DWORD, PHALF_PTR, and friends, so my issue is not so much “don’t know how to grok this” as it is “we finally have sane, universal type names and you’re throwing them away.”

Sure, the _t suffix may be an eyesore but I’ll take size_t over “size” any day.

loeg2• 3 years ago

The u32, i8, etc type aliases are the least offensive parts of this to me, even though I rarely see them in C code. I think those are pretty clear.

b32, size (ptrdiff_t), usize (size_t), nothing for ssize_t... what? Those are unidiomatic and also kind of weird. The macros... some are fine, some are weird.

If this makes the author more productive in C, it might behoove them to see if a higher level language like Rust would meet their needs.

hyc_symas• 3 years ago

typedef all structs - yes, helps with conciseness. Use typedefs liberally, I say. But only typedef the things themselves, not pointers to the things. You can always use (type *) when you need a pointer. In particular, for function pointers, typedef the function, not the function pointer. Then you can use the function typedef for function declarations too, which gives you parameter type checking without needing to fix declarations everywhere if you change a function signature. I see most C codebases get this one wrong, typedef'ing the function pointer and still needing to manually write out all function declarations for that pointer definition.

I'm not sold on the structs as return types thing. I prefer just a numeric error code as a return value, and out parameters for any other returns.

jpcfl5• 3 years ago

I prefer to use typedef's for opaque structs to emulate classes with all private fields, and use 'struct' for plain ol' data structures. Classes should only be accessed via functions, while structs can be accessed directly.

I think this is more-or-less a C/POSIX standard convention. E.g., `pthread_t` vs. `struct stat`.

lelanthran20• 3 years ago

I prefer to use typedef's for opaque structs to emulate classes with all private fields, and use 'struct' for plain ol' data structures. Classes should only be accessed via functions, while structs can be accessed directly.

Totally agree, I even wrote this as a blog post: https://www.lelanthran.com/chap9/content.html

yvdriess• 3 years ago

It's definitely part of the linux kernel coding style: https://www.kernel.org/doc/html/v4.10/process/coding-style.h...

PH95VuimJjqBqy• 3 years ago

But only typedef the things themselves, not pointers to the things.

I agree with this. One of the things I dislike about SDL_net, etc, is they do exactly what you're describing. It's a pointer but they typedef it as if it's a value type.

I understand the intent but imo that's very icky.

comex4• 3 years ago

#define sizeof(x) (size)sizeof(x)

I'm guessing this is lacking an outer pair of parentheses (i.e. it's not `((size)sizeof(x))`) on the grounds that they're unnecessary. In terms of operator precedence, casting binds tightly, so if you write e.g. `sizeof(x) * 3`, it expands to `(size)sizeof(x) * 3`, which is equivalent to `((size)sizeof(x)) * 3`: the cast happens before the multiplication. Indeed, casting binds more tightly than anything that could appear on the right of sizeof(x) – with one exception which is completely trivial.

But just for fun, I'll point out the exception. It's this:

    (size)sizeof(x)[y]

Indexing binds more tightly than casting, so the indexing happens before the cast. In other words, it's equivalent to `(size)(sizeof(x)[y])`, not `((size)sizeof(x))[y]`.

But you would never see that in a real program, since the size of something is not a pointer or array that can be indexed. Except that technically, C allows you to write integer[pointer], with the same meaning as pointer[integer]. Not that anyone ever writes code like that intentionally. But you could. And if you do, it will compile and do the wrong thing, thanks to the macro lacking the extra parentheses.

…On a more substantive note, I quite disagree with the claim that signed sizes are better. If you click through to the previous arena allocator post, the author says that unsigned sizes are a "source of defects" and in particular the code he presents would have a defect if you changed the signed types to unsigned. Which is true – but the code as presented also has a bug! Namely, it will corrupt memory if `count` is negative. You could argue that the code is correct as long as the arguments are valid, but it's very easy for overflow elsewhere in the code to make something accidentally go negative, so it's better for an allocator not to exacerbate the issue.

With unsigned integers, a negative count is not even representable, and a similar overflow elsewhere in the program would instead give you an extremely high positive count, which the code already checks for.

Personally I prefer to use unsigned integers but do as much as possible with bounds-checked wrappers that abort on overflow. Rarely does the performance difference actually matter.

bjourne2• 3 years ago

That's a good catch. The moral of the story is that unless your macro definition expands to a single token (e.g #define X 123) you should always, always, always surround it with parenthesis. Because C's precedence rules are damn complicated.

mananaysiempre• 3 years ago

Because C's precedence rules are damn complicated.

This particular part is not actually complicated: the postfix operators bind the most tightly, then the prefix ones, then the infix ones. (The last part is quite messy, though.)

So (int)x[y] parses the same way as, for example, *p++, which should be familliar to a C programmer.

comex4• 3 years ago

(self-reply) One more thing.

I could use _Bool, but I’d rather stick to a natural word size and stay away from its weird semantics.

This is even more subjective, but personally I like _Bool's semantics. They mean that if an expression works in an `if` statement:

    if (flags & FLAG_ALLOCATED)

then you can extract that same expression into a boolean variable:

    _Bool need_free = flags & FLAG_ALLOCATED;

The issue is that `flags & FLAG_ALLOCATED` doesn't equal '0 if unset, 1 if set', but '0 if unset, some arbitrary nonzero value if set'. (Specifically it equals FLAG_ALLOCATED if set, which might be 1 by coincidence, but usually isn't.) This kind of punning is fine in an `if` statement, since any nonzero value will make the check pass. And it's fine as written with `_Bool`, since any nonzero integer will be converted to 1 when the expression is implicitly converted to `_Bool`. But if you replace `_Bool` with `int`, then this neither-0-nor-1 value will just stick around in the variable. Which can cause strange consequences. It means that

    if (need_free)

will pass, but

    if (need_free == true)

will fail. And if you have another pseudo-bool, then

    if (need_free == some_other_bool)

might fail even if both variables are considered 'true' (i.e. nonzero), if they happen to have different values.

_Bool solves this problem. Admittedly, the implicitness has downsides. If you're refactoring the code and you decide you don't really need a separate variable, you might try to replace all uses of `need_free` with its definition, not realizing that the implicit conversion to _Bool was doing useful work. So you might end up with incorrect code like:

    if ((flags & FLAG_ALLOCATED) == true)

Also, if you are reading a struct from disk or otherwise stuffing it with arbitrary bytes, and the struct has a _Bool, then you risk undefined behavior if the corresponding byte becomes something other than 0 or 1 – because the compiler assumes that the implicit conversion to 0 or 1 has been done already.

cozzyd• 3 years ago

I always just use !! for this case.

billforsternz2• 3 years ago

This is all very good and very, ahem, true. But (and it's a big butt);

if (need_free == true)

Is such a horrible code smell to me. You have a perfectly good boolean. Why compare it to a second boolean to get a third boolean?

if (need_free)

if (!need_free)

for the opposite case is so much better.

I will admit that in my world this leaves

if (need_free == some_other_bool)

as something I don't have a particularly comfortable way of doing safely.

jstimpfle7• 3 years ago

(size)(sizeof(x)[y])

Actually, and this is probably surprising to many, this is equivalent to

    (size)(sizeof ((x)[y]))

sizeof is not a function but a unary operator, and indexing (as well as function calling...) binds stronger than the sizeof operator. It is not a function, not even syntactically! Hence why I strongly prefer putting a space after the sizeof keyword, and to not use parens for the operand unless needed.

https://en.cppreference.com/w/c/language/operator_precedence

So the "correct" way to define the macro is

#define sizeof(x) ((size)(sizeof (x)))

jeanlucas• 3 years ago

I wish I could work with C again

Quekid52• 3 years ago

I wish nobody would have to.

(Haha, only serious.)

sys_64738• 3 years ago

C is wonderful so if you an find a project at work with a lot of C code then it'll remain forever. All these other fad languages will die before C ever does.

josephg4• 3 years ago

I'm hopeful for Zig as a modern replacement for C. It feels modern like rust, but still with C's lightness.

bjourne2• 3 years ago

I like it a lot. Especially the part about ditching const qualifiers. They clutter function declarations, don't make the intent any clear, and almost never improve performance. Restrict, on the other hand, I've found makes the compilers emit better code in many cases.

But I don't like using 1 and 0 instead of booleans. Many standard C functions (fclose for example), return 0 on success. Better to be explicit here.

pylua• 3 years ago

I like using the const keyword, and believe it serves a real purpose with readability. I feel like most things are read access by default which is why it seems cluttered. I believe rust gets immutable by default correct .

dundarious2• 3 years ago

I use an exitint typedef to signify "0 is success, non-0 is failure" and boolint equivalent to his b32. Not typesafe of course, so it's just info for fallible humans.

thetic4• 3 years ago

#define sizeof(x) (size)sizeof(x)

Undefined behavior[1]

#define assert(c) while (!(c)) __builtin_unreachable()

Undefined behavior[1]

I’ll cast away the const if needed.

Undefined behavior[2]

The assignments are separated by sequence points, giving them an explicit order.

I don't believe assignments are sequence points and only the function call is.

[1] https://en.cppreference.com/w/c/language/identifier#Reserved...

[2] https://en.cppreference.com/w/c/language/const

WalterBright15• 3 years ago

#define assert(c) while (!(c)) __builtin_unreachable()

And people keep telling me that nobody uses the C preprocessor to define their own syntax any more!

dundarious2• 3 years ago

> I’ll cast away the const if needed.
Undefined behavior[2]

To be clear, it's only UB if the object was defined const, which is the case given he wrote:

One small exception: I still like it as a hint to place static tables in read-only memory closer to the code. I’ll cast away the const if needed.

So you are correct on this point. Funnily enough, such objects are relatively rare IME, so I had to double-check to see that he was advocating it specifically in the rare case where it must not be applied.

comex4• 3 years ago

Undefined behavior[2]

Given that this particular undefined behavior usually causes crashes in practice, I expect the author is talking about casting away the const but not actually writing to the pointer. Which is legal.

thetic4• 3 years ago

The legal cases in which he needs to cast away const could be avoided if the arguments to called functions were appropriately qualified.

paulddraper4• 3 years ago

Or a common situation is mutable -> const -> mutable.

And that is legal.

LegionMammal9782• 3 years ago

> I’ll cast away the const if needed.
Undefined behavior[2]

How so? As the page you linked mentions, simply casting 'const T *' to regular 'T *' is well-defined; it's only modifying a const object through the pointer that's UB (C17 6.7.3/7).

I don't believe assignments are sequence points and only the function call is.

Assigments within expressions don't create sequence points. However, the expression of an expression statement is a full expression (i.e., not a subexpression of another expression), and there is a sequence point between each pair of full expressions (C17 6.8/4). In other words, the semicolons create sequence points.

drpixie2• 3 years ago

While there are a few disagreeable points, I like the article.

I've always felt that C is unfairly maligned. Yes, it's very low level, it's meant to be. Yes, it lets you shoot yourself in the foot, but what language doesn't?

Most of the problems with C are really issues with the standard library, the Unix (now Posix) interfaces, and the string type.

None of these are actually part of C, but are part of how C is normally used. So those problems can be avoided, and use C for what it's good at.

edvinbesic• 3 years ago

I've always felt that C is unfairly maligned. Yes, it's very low level, it's meant to be. Yes, it lets you shoot yourself in the foot, but what language doesn't

Isn’t it a beauty of lower level languages that creating higher level abstractions provides more value?

edit: typo

eldenring• 3 years ago

Yes, it lets you shoot yourself in the foot, but what language doesn't?

Good lord.

drpixie2• 3 years ago

Well ... Name a language is which you categorically cannot "shoot yourself in the foot"!

slimsag• 3 years ago

It's not unfairly maligned, it's just that everyone remembers their college/university 'learning experience' which made no distinction between C/C++, they were told to use the Borland compiler, and when trying to learn printing "hello world" they only got a `segmentation fault` error instead of a stack trace. When they asked why it's so hard, they were told C/C++ is hard - so they dropped the class.

Then they picked up a JS or Python class, were told high-level languages are easy and viola! they started to understand programming.

That's the reason people are spiteful of it. They had a terrible learning experience right out the gate.

jes5199• 3 years ago

do compilers like gcc support stack traces now?

WalterBright15• 3 years ago

Interesting how my experience has led me in a different direction:

https://dlang.org/blog/2023/10/02/crafting-self-evident-code...

(The article is crafted around D, but the principles apply to C as well.)

keyle• 3 years ago

Fun read.

    What happened to the conditional expressions? Move them to the interiors of doX() and doZ().

That was an interesting point. Not sure that it's always valid but I guess it depends where you want the abstraction to lay, and how it affects the mental construct around the code.

e.g.

    deleteRecords();

is not better than

    if let x = deadRecords()
       deleteRecords(x);

Sure, it looks messier but there is value is showing upfront that you're pruning and not wiping.

If the author wisely renames his function e.g. pruneDeadProjects(), yes. But merely moving the the condition within the function can be dangerous for context and be a leaky abstraction.

WalterBright15• 3 years ago

Finding the right abstraction isn't always easy. Sometimes if I just put it down and let it slosh around in my brain for a few days, it comes to me.

Like your idea of pruneDeadProjects()!

juunpp• 3 years ago

How do you not use const for arguments of data types that are too costly to pass by value?

progfix• 3 years ago

Usually if it is too costly, then you pass it via a pointer.

jpcfl5• 3 years ago

Parameters and functions

No const.

Please don't. `const` is incredibly valuable, not only to the reader, but to the compiler.

Take for example:

  int Foo_bar(Foo const* self);

Just looking at this signature, I know that calling `bar()` will not modify the state of the object. This is incredibly valuable information to the reader.

Furthermore, if I want to create a `Foo` constant, I can only call this function if it is `const`.

  static Foo const a_foo = FOO_INIT(&some_params);
  return Foo_bar(&a_foo); // Will not compile without 'const' in function

`const` is valuable to the compiler, since `a_foo` can be placed into ROM on some platforms like MCUs, saving precious RAM.

paulddraper4• 3 years ago

Agreed; const is one of those features that is so good I wish a lot of other languages (e.g. java) had it.

epcoa5• 3 years ago

const in C and C++ are an abomination. On a pointer they don’t tell the compiler to do shit, because they can’t.

That I can agree with TFA. However I agree with the GP that dismissing it entirely is a little misplaced. It serves as a hint/documentation and I think the article undersells the value of rodata (not the pointer use of const which is basically shit).

I mean I have seen at least a few SIGSEGV/aborts due to attempted writes to ro memory. Also like, one of the few modern justifications for C, embedded, const still has important link time meaning.

skovati• 3 years ago

FWIW, Java does have the "final" keyword.

david2ndaccount3• 3 years ago

You only know there are no mutations if Foo itself does not contain any indirections. Additionally, the compiler generally cannot assume that Foo_bar does not modify Foo as it is legal to cast away const as long as it is not originally a variable declared as const (so in your static Foo example it would be UB to cast away const).

static + const is valuable, but const parameters are merely a convention, there is no actual enforcement around them and due to aliasing the compiler generally can’t assume the parameter doesn’t actually change anyway.

lelanthran20• 3 years ago

Additionally, the compiler generally cannot assume that Foo_bar does not modify Foo as it is legal to cast away const

No, but it can warn you!

The type is meant to capture programmer intention, and if you use `const` the compiler can warn you that your intention does not match the intention of the existing code (like, the intention of the author who wrote Foo_Bar).

jpcfl5• 3 years ago

True. I should rephrase to say `const` strongly suggests that a function does not change the observable state of a variable.

glitchc2• 3 years ago

I'm afraid you are mistaken. In particular for pointers, const does not guarantee that the memory at the location pointed to won't change. Const only guarantees that the address itself doesn't change.

kibibu• 3 years ago

Should perhaps be

    int Foo_bar(const Foo * self);

jpcfl5• 3 years ago

const does not guarantee that the memory at the location pointed to won't change

I didn't say this. I said a `const` function tells the reader that the state of an object doesn't change.

Another reader correctly pointed out that there are ways to modify the state of a `const` parameters (indirection and const cast), but I would argue that such an API is poorly-designed.

To qualify my original comment, a reader only knows a function doesn't change an object's state if the API is well-designed.

__MatrixMan__• 3 years ago

Sorry for going off topic, but something fun I've learned lately is that in Nim (which compiles to C) changing:

let x = foo()

... to ...

const x = foo()

...runs foo at compile time to get the value. I dunno I just thought it was neat.

Uptrenda• 3 years ago

IMO, defining your own types is one step too far. Now everyone who is already familiar with C types has to learn your own quirky system to understand one program. I think it does probably make sense to be specific about the sizes though e.g. using uint32_t over just uint (and expecting to receive some architecture-dependent size you might not get with uint.) These types should be defined in the right header (I think it depends on compiler?) It's been a while since I wrote any amount of C so my apologizes if this isn't correct.

voxl• 3 years ago

they're not quirky types in the least...

guidoism2• 3 years ago

I agree. A lot of languages have settled on those same names or something similar. We don’t live in a world with a single word size anymore so carrying bit length in the name is critical, and so is keeping identifier names short. His trade off is exactly the one I would make.

outsomnia3• 3 years ago

In isolation, they're not crazy.

But much C code is bringing in library headers which contain their author's own pet choices for these, which inevitably are not the same and the result is extremely confusing when you have that in play as well as the stdint.h ones.

The kernel contains a mixture of "pet" types like u32 and stdint ones, it's already confusing.

He also does make a "crazy" choice later to call his string class "s8" which clashes with his nomenclature here.

lelanthran20• 3 years ago

they're not quirky types in the least...

But they are buggy (correct code cannot depend on the sign of `char`), which is usually the result of typedefing primitive types to save typing 3 characters on each use.

colejhudson• 3 years ago

I mean, being a bit glib here, but a lot of programming is dealing with someone else's type system.

Moreover, for those of us who write C fairly often, the mnemonics here are familiar.

Actually, as custom type systems go, this one is pretty elegant. Reminds me of Rust.

kristopolous• 3 years ago

Speaking of type systems, I read glib as g-lib a few times and tried to understand how you were talking about the GNU lib in that sentence.

oaiey4• 3 years ago

Yeah but not for basic types. Also, most code mingles sooner or later with other code. Than this is just ugly.

petabytes• 3 years ago

It's pretty much the same types you see in Rust or Zig, and I think Linux even uses some of the same types.

oaiey4• 3 years ago

Yeah, and C/C++ has these since three times the age of Rust. I also find them beautiful but not consistent.

pwdisswordfishc2• 3 years ago

With slightly different semantics; as I recall, the Linux uXX and iXX types have natural alignment (equal to size), while stdint.h types are not required to.

rkagerer• 3 years ago

The author did qualify it with personal coding style. Frankly the standard types are too verbose and I wish this guy's elegant and clear list had been the one that was adopted way back when.

lelanthran20• 3 years ago

The author did qualify it with personal coding style. Frankly the standard types are too verbose and I wish this guy's elegant and clear list had been the one that was adopted way back when.

They didn't adopt it for the same reason that it is a bad idea now - too many programs already contained at least one variable named after his types.

If the standard had adopted his convention, too many programs will break, which is why his convention is currently unsuitable for any existing project.

iforgotpassword3• 3 years ago

That ship has sailed ages ago. There are some things you should just accept about C, or any programming language really. Just because you can do something doesn't mean you should do something. I don't know how many years of experience in C this guy has, but this is a "been there, done that" case for me. I stick to stdint and stdbool today, and even if only half the code/libs I interface with do that, it's already worth the extra _t-typing all the time. Just the fact that they use the i prefix for signed, and s for string has a high chance that his s8 string type gets confused with an 8-bit signed int.

But as you say, it's a personal style, and the author seems to be aware of that:

I’m not saying everyone should write C this way, and when I contribute code to a project I follow their local style.

Because that's by far the most important rule to follow in any language.

I think the rest is less controversial, the 0 vs. NULL thing has been going on forever; I didn't check recently but I'd assume "const somestruct *foo" would still sometimes help out the compiler to optimize vs. the non-const version.

marwis• 3 years ago

In case of winapi you can actually generate your own headers following the style you want, see for example https://github.com/microsoft/cppwin32

WalterBright15• 3 years ago

The reality is that C `int` is 32 bits in size.

Sure, that's not true for 16 bit targets. But are you really going to port a 5Mb program to 16 bits? It's not worth worrying about. Your code is highly unlikely to be portable to 16 bits anyway.

The problem is with `long`, which is 32 bits on some machines and 64 bits on others. This is just madness. Fortunately, `long long` is always 64 bits, so it makes sense to just abandon `long`.

So there it is:

    char - 8 bits
    short - 16 bits
    int - 32 bits
    long long - 64 bits

Done!

(Sheesh, all the endless hours wasted on the size of an `int` in C.)

consp• 3 years ago

Which are minima, but in practice they represent the width.

Findecanor• 3 years ago

Yet another issue is that `char` is signed on some platforms but unsigned on others. It is signed on x86 but unsigned on RISC-V. On ARM it could be either (ARM standard is unsigned, Apple does signed).

I therefore use typedefs called `byte` and `ubyte` wherever the data is 8-bit but not character data. I also use the aliases `ushort`, `uint` and `ulong` to cut down on typing. On the other hand, the types in <stdint.h> are often recognised by syntax colouring in editors where user-defined types aren't.

self_awareness2• 3 years ago

Isn't "int" 64-bit on some (rare) architectures?

rurban2• 3 years ago

C is also used on embedded. It's even there the default language.

slikrick3• 3 years ago

so... what I'm seeing is that C got it wrong relative to the way things actually work and get used.

the fact that you had to have tribal knowledge about all of this is why C shouldn't stay for the long term and we should phase out languages into ones with stronger more correct defaults.

would a new programmer use "long long"? would they notice immediately that things didn't work if they didn't use it?

Rust got it correct by labeling the bits with the type directly

stephc_int134• 3 years ago

Long Long is ridiculous and often confusing.

Now, what about SIMD types?

What about 16bits floats?

Using the short size convention we have easy and logical answers.

The reason why new languages like Rust and Zig are using those conventions is not random, types naming (and stdlib) is a weak point of C (and C++).

Luckily they are not set in stone, we can choose different and reasonable conventions.

sovande2• 3 years ago

Exactly this (plus floating point types and unsigned qualifier) and done. It’s standard C, there is no need to invent yet another unnecessary “type” system for standard C native types. I do like bool though.

aidenn0• 3 years ago

I swear I've seen 128-bit "long long" types.

Am4TIfIsER0ppos• 3 years ago

Wait... where's plain "long"? I know, you probably know, but that is why you use explicit sizes where you can.

kazinator13• 3 years ago

The Motorola 68K family has been targeted by C compilers configured with 16 bit int.

kazinator13• 3 years ago

Choosing integer sizes in C is pretty easy. The standard guarantees certain minimum ranges.

1. Consider the char and short types only if saving storage is important. Do not declare "char number_of_wheels" for a car, just because no car has anywhere near 127 wheels, unless it is really important to get it down to one byte.

2. Prefer signed types to unsigned types, when saving storage is not important. Unsigned types bend the rules of arithmetic around zero, and mixtures of signed and unsigned arithmetic add complexity and pitfalls. Do use unsigned for bitmasks and bitfields.

3. Two's complement is ubiquitous: feel free to assume that signed char gives you -128, and short gives you -32768, etc. ISO C now requires two's complement.

3. Use the lowest ranking type whose range is adequate, in light of the above rules: rule out the chars and shorts, and unsigned types, unless saving space or working with bits.

For instance, for a value that ranges from 0 to 65535, we would choose int. If it were important to save storage, then unsigned short.

The ISO C minimum required ranges are:

  char                 0..255, if unsigned; -128..127 if unsigned, therefore: 0..127
  signed char          -128..127
  unsigned char        0..255
  short               -32768..32767
  unsigned short       0..65535
  int                  -32768..32767
  unsigned int         0..65535
  long                  -2147483648..2147483647
  unsigned long        0..4294967295
  long long            9223372036854775808..9223372036854775807
  unsigned long long   0..18446744073709551615

If you're working with bitfields, and saving storage isn't important, start with unsigned int, and pick the type that holds all the bits required. For arrays of bitfields, prefer unsigned int; it's likely to be fast on a given target. It's good to leave that configurable the program. E.g. a good "bignum" library can easily be tuned to have "limbs" of different sizes: 16, 32 or 64 bit, and mostly hides that at the API level.

If you're working with a numeric quantity, remove the unsigned types, shorts and chars, unless you need to save storage (and don't need negative values). Then pick the lowest ranking one that fits.

E.g. if saving storage, and don't need negative values, search in this order: char, signed char, unsigned char, short, unsigned short, long, unsigned long, long long, unsigned long long.

If saving storage, and negatives are required: signed char, short, int, long, long long.

If not saving storage: int, long, long long.

If the quantity is positive, and doesn't fit into long long, but does fit into unsigned long long, that's what it may have to be.

ChrisRR2• 3 years ago

Oh I don't even know where to start with this. Given that C is the lingua franca of embedded development, and each processor and compiler has different opinions of what an int is, I would never claim that an int is 32 bits.

It's just so much less error prone to define a uint32_t. That's guaranteed to be the same

Nursie2• 3 years ago

These types should be defined in the right header

stdint.h

It's always been amazing to me how many different projects I've worked on (not that I've been in professional C for about 7 years now)) that include their own painstaking recreation of this file.

Reusing them and effectively translating them just to your own name is just annoying to the reader IMHO. I am reminded of a C++ project I worked on, where I questioned the extensive use of typedefs around collections of things, various forms of references and compound objects etc. I was informed by one of the more experienced C++ folks that it made the code easier to comprehend.

Later I saw the typedef cheat-sheet sellotaped to the side of his monitor...

gallier23• 3 years ago

For bool it's even worse.

cesarb• 3 years ago

It's always been amazing to me how many different projects I've worked on (not that I've been in professional C for about 7 years now)) that include their own painstaking recreation of this file.

How many of them started before stdint.h existed? AFAIK, it's a somewhat recent addition to the C language, and IIRC, for a long time even after it became part of the C standard, some popular C compilers still didn't have it.

the_mitsuhiko• 3 years ago

The big issue with custom integer types is that while they are awesome in the implementation files, they are problematic for libraries in headers. And if you want to avoid a divergence between header and implementation files you're kinda stuck with the inttypes.h ones in practice.

pwdisswordfishc2• 3 years ago

IMO, defining your own aliases for stdint.h types is innocent enough, but manually defining prototypes for Win32 calls instead of including standard headers is one step too far. You don’t own the ABI here: things like HANDLE and WPARAM have already changed sizes once, who’s to say ULONG_PTR will stay the same as uintptr_t for all future architectures? There is a good reason why doing the same on Unix is discouraged.

Lockal2• 3 years ago

Just a note: defining own integer types has sense for resource-limited platforms. Most common type I see is something like "dim_t", which is 32-bit or 64-bit depending on use-case. 32-bit integers are often used even on 64-bit platforms in pointer compression schemes (for example, allocate your own heap and only store 32-bit offsets). This not only gives 2x improvement on memory usage for <4GB workloads, but it also improves performance due to better cache locality.

adrianN• 3 years ago

How does it improve locality?

kazinator13• 3 years ago

The u32/i64/... naming system is pretty common.

Assuming you can trust those types to be what they look like, the code is readable.

I've worked with C for well over 30 years; custom typedefs are par for the course. Work with OpenMAX libs? You have OMX_U32. On Windows? You have DWORD. Using Glib? guint32 ...

mattpallissard• 3 years ago

Now everyone who is already familiar with C types has to learn your own quirky system

Oh I dunno. On one hand yeah learning a quirky system is an annoyance at times. On the other hand when you're coming from a language with a real type system dealing with custom types is standard operating procedure.

I've had to patch a lot of C over the years. I can't say I've ever been bothered by types. It's always the usual suspects; hard coded offsets peppered throughout the codebase, stack smashing, baby's first callback implementation, "parsing" that omits lexing/tokenizing, archaic business logic that may-or-may not have ever been correct.

AlchemistCamp• 3 years ago

You can just #include <stdint.h> to get those types, at least in the environments I’ve worked in.

EPWN3D• 3 years ago

lol "no const". This is really groundbreaking stuff. Let's take a memory-unsafe language and make it even less safe.

bandrami3• 3 years ago

Rugby has much lower injuries than American football, it's often argued because rugby players don't use the helmets and padding and so are less willing to make catastrophically dangerous hits.

waffletower• 3 years ago

Would be great to see the author's treatment of memory allocation and lifecycle for complex data types.

ok123456• 3 years ago

See his posts about arena allocations.

kazinator13• 3 years ago

#define sizeof(x) (size)sizeof(x)

That breaks any macro that uses sizeof in its expansion, and subtly changes any code snippet you might bring into the code that uses sizeof, even if those macro are defined first.

Speaking of which, if you define a macro for a C keyword before including any standard header, the behavior is undefined.

It's an unparenthesized unary expression, which has a lower precedence than postfix. sizeof(x)[ptr] will turn into (size)sizeof(x)[ptr] which parses as (size) ( sizeof(x)[ptr] ).

lsh123• 3 years ago

I wrote and still maintain an open source C project for 20+ years. Once a year I get a new guy coming in and telling me I am doing it wrong: you should typedef all data types, you should stop using const, and so on. It stopped being funny after the first couple times.

laserbeam• 3 years ago

I'm getting an "I don't use const, and here's my view on it" vibe from the author much more than "you shouldn't use const". I'm really not getting any demand that you change your coding style, just someone reflecting on their work and explaining it to others. And... Whether I agree with their choices or not, I find that very cool and informative.

SoftTalker• 3 years ago

And, he also says "I’m not saying everyone should write C this way, and when I contribute code to a project I follow their local style."

outsomnia3• 3 years ago

It wasn't clear to me if he's talking about const as a variable declaration qualifier - I never used it - or const in pointer types, which is very useful.

P_I_Staker4• 3 years ago

I will say that using const can make a huge mess of code, especially if you care about adhering to (very reasonable) guidelines.

There's a really good chance you will either have to promote or cast away the const, which I hate.

I tend to agree regarding not using const. It's been a while, so I don't have an example off the top of my head, but it's incredibly easy to break the const mechanism and have to deal with these annoying flaws.

I've just seen this go really bad with any kind of code that has a split responsibility between teams. Eventually you will have to pass to a non-const interface, that you aren't supposed to change.

So perhaps it makes sense if you have control from the top down and can ensure that the constness is maintained, or completely not, if it ends up non-const (then you could also try to move the interface to const, if it truly is)...

... I also suspect in many projects you'd just have to come to the conclusion that nothing can be const'd, because it ends up non-const anyway. Thus leading to the conclusion "just don't use const".

P.S. I'm a bad boy that didn't read TA yet. This is just based on my past experience where we didn't really have the authority to change stuff in the stack... often times there was eg an MCU interface at the end that was non-const... guess we could contact the silica manufacturer... sure they'll get right on that.

rewgs• 3 years ago

I'm not a C developer, so I have to ask: why in the world would you not use const?

jstimpfle7• 3 years ago

It's more work. Not only to put all the annotations correctly, but only because it causes some real headaches. It's easy (implicit) to transition from non-const to const 1 pointer level deep. But the other way around -- it's really awkward to "remove" a const.

The strstr() signature is probably the shortest example / explanation why. To implement strstr(), you have to hack the const away to create the return value. Alternatively, create a mutable_strstr() variant that does the exact same thing. This is the kind of boilerplate that we don't want in C (and that C is bad at generating automatically).

Think about it this way: Real const data doesn't exist. It always gets created (written) somewhere, and usually removed later. One way where this works cleanly is where the data is created at compile time, so the data can be "truly" const, and be put in .ro section, and automatically destroyed when the process terminates. But often, we have situations where some part of the code needs to mutate the data that is only consumed as read only by other parts of the code. One man's const data is another man's mutable data.

In C, the support for making this transition work fluently is just very limited (but I think it's not great in most other languages, either).

P_I_Staker4• 3 years ago

You want to avoid promoting or casting away the const. If you start using const, you almost inevitably wind up with a mismatch.

This introduces flaws in the type system. I wish I had a better breakdown on the impact of these concerns, but I'd rather not worry at all.

Anyway, if you don't use const, this goes away. Bear in mind the minor amount of "safety" it provides, because you can just ignore it later, as you arguably tend to be doing anyway when you pass a const to non-const or visa versa.

Inevitably, outside of really small insular project (and often times even then), there's something down the line that winds up being non-const that you don't want to change.

C developers of this mindset tend to just come to the conclusion that you will immediately break the type system, just give up on the whole game.

Edit adding at least on example:

Example: You define as const and remove the const later. If anything writes to the non-const, this is undefined behavior

Example: I believe the above is actually true for const promotion if you modify the non-const version... I think this is only after the call (edit. ie after it become const, really interest in the answer).

No Undefined behavior

/* I imagine this would be okay */

si_non_const = si_non_const + GetMagicValue();

/* Const is promoted here */

const int fparam = si_non_const;

/* Writing to fparam is undefined past here */

f_const(&fparam);

Undefined behavior

/* I imagine writing, after using as const is also not defined, but is fine at this point */

si_non_const = si_non_const + GetMagicValue();

/* Here we now have a constant value that will never be written to */ const int fparam = si_non_const;

f_const(&fparam);

/* I think this would also be UB, even though it's accessed through a different symbol */

si_non_const = si_non_const + GetMagicValue();

Interested in other opinion, maybe will think on later... would it be valid for the compiler to remove that last assignment?

Edit: Sorry, this is unreadable, if you put a space between the not undefined, and undefined it's easier

f1shy2• 3 years ago

Funny enough, the take on const in the only thing I agree with in the whole post…

rurban2• 3 years ago

I"m even not agreeing with the const part. The standard did define const API"s, so why shouldn"t we follow? I know that C const are only half of C++ consts, but still. Still catching const errors somewhere because I do use const in APIs.

I only agree with "Declare all functions static except for entry points".

s8(s) is only for literal strings, it should be called s8_c instead and keep s8 for the default ctor.

The struct return part is okay, but I"ve never used. This is not Common Lisp.

travisgriggs• 3 years ago

Pretty much agree with most of this. My own personal evolved style is pretty similar. I'm suspect this kind of pragmatic style offends the theoretic and the academic. That can be intimidating. I'm glad at least one other person out there is like me.

uwagar• 3 years ago

looks like u tabstop at 4, i prefer 2. other than that our styles match :)

Lockal2• 3 years ago

typedef ptrdiff_t size;

This reminds me of "#define max ..." in Windows.h. Not as bad, but if you autoreplace `sizeof(ptrdiff_t)` with `sizeof(size)`, good luck, because it will output size of type of size variable, if it exists in the scope.

bandrami3• 3 years ago

Yeah that's why the uppercase/lowercase hardline is a good one. Even Lisp, where free variable capture is a legitimate design pattern, has troubles with this.

0xedd• 3 years ago

code style personal

You missed the point of code style.

lelanthran20• 3 years ago

In general, the style the author has adopted is to introduce brevity where he can, and use wrappers over what would have been standard and idiomatic C code. In most situations, these conventions aren't good in a non-solo project, because they simply aren't as obvious to the programmer.

He says so himself:

I don’t intend to use these names in isolation, such as in code snippets (outside of this article). If I did, examples would require the typedefs to give readers the complete context. That’s not worth extra explanation. Even in the most recent articles I’ve used ptrdiff_t instead of size.

You require extra work to understand his basic types before reading even a short snippet, so he doesn't use it when he wants people to read short snippets.

Introducing additional stuff the programmer must remember that does not add any safety is pointless busywork.

A non-complete summary of his conventions:

1. typedef standard typenames to 3-char symbols,

2. remove qualifiers like const,

3. use macros to reduce the amount of typing the programmer does,

4. typedef all structs (and enums too, I assume)

5. A macro-ized string-typed with prefixed-length.

Starting with the fundamentals, I’ve been using short names for primitive types. The resulting clarity was more than I had expected,

This isn't clear: `int8_t` is a lot clearer to a C programmer than `i8`, because a C programmer has already internalised the pattern of the stdint.h types. This is going to lead to subtle bugs as well: quick, according to his convention, what is the % specifier for `byte`?

You can use %c, but that gives you an ascii character (which is not what we think of when we say 'byte').

If you use PRIu8 the compiler might give warnings because `char` might be signed. The best option is to just not use `byte` and use `uint8_t` instead (or, in his system, `u8`).

Same with `b32` vs `i32` - it's a distinction without a difference and mixing these types won't give compiler warnings, while it is almost certainly an error on the part of the developer. Use `bool` if you don't like `_Bool`.

In general I try to take advantage of whatever typing C provides; I don't try to subvert it because I want the compiler to warn me when my intention doesn't match the code I wrote.

No const. It serves no practical role in optimization, and I cannot recall an instance where it caught, or would have caught, a mistake.

I disagree with dropping `const`.

1. It's useful as an indicator to the caller that the returned value must/must not be freed. It's a convention I use that makes it easy to visually spot memory leaks.

Of the two functions below, it's clear to me which one needs the returned value `free()`ed and which one doesn't.

     const char *replace_substring (const char *src, const char *pat, const char *replacement);
     char *replace_substring (const char *src, const char *pat, const char *replacement);

2. It actually does catch a lot of problems, because the compiler warns me when I attempt to modify a value that some other code I wrote never intended to be modified. It's about intention, and when I know it is safe to modify the `const` value, then I have to explicitly cast away the const to compile my program. Anyone reading the program will know that the modification of the const-qualifed value is intentional, and therefore safe.

#define s8(s) (s8){(u8 *)s, lengthof(s)}

This is interesting. I will try this out in my next project. I do think that there'll be quite a few compiler warnings for sign-mismatch though. This is the second "I wonder what the sign is" question for programmers reading his code - it means that his code has to compile with the flags that he compiles it with (I assume he's passing a flag to force chars to a particular sign). You can't simply compile his code in another project unless you copy his flags, and those flags may conflict with the new projects flags.

I also wish that he'd showed a few examples of how having the length helps - what is presented in the post doesn't show any additional string safety over using nul-terminated strings. All those macros, including the one that creates the struct, could be written to operate on null-terminated strings. In essence, the length can be simply unused for everything! Where's the safety!?

It’s also led to a style of defining a zero-initialized return value at the top of the function, i.e. ok is false, and then use it for all return statements. On error, it can bail out with an immediate return.

I use a similar pattern, but I use `goto cleanup` on all errors; you can't, as a general pattern, return early in a non-trivial C function without leaking resources. You can, as a general pattern, `goto cleanup` in every C function to clean up resources. I prefer the general pattern that I use everywhere rather than having to ensure that all resources acquired up to that particular return statement are released.

rather than include windows.h, write the prototypes out by hand using custom types.

I think this is a very bad idea: you can't depend on the headers not changing after a compiler or library update. Sure, maybe in practice, all the Windows types and declarations don't change all that much, but I wouldn't want to be the developer trying to hunt down a bug because the interface to some function has changed and the compiler isn't giving me errors.

All in all, I dunno if I would look forward to working on a team with these conventions - the code is harder to read, doesn't work in isolation, needs custom flags, and introduces a string type without introducing any string safety with it.

zeroCalories• 3 years ago

I think C really needs an update to the standard library that includes these shorter types. Seems like a fine list though.

Some of my own style changes this year:

I try really hard to write functional code. Mainly try to keep functions pure, and write declarative code. I find that this makes the code easier to write(not necessarily read), and I'm less scared of bugs.

I also avoid malloc unless I absolutely need it. You can usually preallocate space on the stack or use a fixed length buffer, which pretty much avoids all fears of memory leaks or use after free type bugs. You will sometimes waste memory by allocating more than you need, but it's a lot more predictable.

quelsolaar• 3 years ago

You can declare flexible array member strings with literals like this:

#define DECLARE_STRING(variable_name, string) struct{size_t allocated; size_t used; char string[sizeof(c_string)];} variable_name ## internal = {.allocated = sizeof(c_string) - 1, .used = sizeof(c_string) - 1, .string = c_string}; MyString *variable_name = &variable_name ## internal

Its a lot of C99 magic, so it may not be what you want but it is possible.

jll29• 3 years ago

The notion of "personal style" is problematic, even for hobby projects, because (good) programming is ultimately a social activity.

Even Linux started as a personal project, but because of its quality and the need it met it quickly spread. So please write your code in such a way that experienced other C programmers can read it easily.

In isolation, I like some of his ideas, but some issues with C remain, and he is perhaps just to comfortable with C to jump ship and embrace Rust, which has many things he likes and more (e.g. no buffer overflows by design).

pif• 3 years ago

No const.

I stopped reading there. I wish this guy a happy coding (and non-coding) life, but I hope we never work together.

cryo• 3 years ago

I'd love to have him in a team. He truly cares exactly how code works and analyzes/fuzzes the hell out of everything.

I don't agree with all stylistic choices in his code, but the level of experience and skills are far above most C developers.

juped• 3 years ago

"Skills" are subjective, but significant "experience" would involve traumatic foot-shooting turning him off most of the things advocated in this post.

da39a3ee2• 3 years ago

#define countof(a) (sizeof(a) / sizeof(*(a)))
#define lengthof(s) (countof(s) - 1)

It makes no sense to use the word "length" to mean one less than the number of items. You could call it maxindexof perhaps.

There may be good arguments for zero based indexing, but we have to also accept that there are downsides. One is that your code has to feature an artificial quantity obtained by subtracting one from a meaningful quantity.

abareplace• 3 years ago

This is length of a null-terminated string, e.g. lengthof("abc").

da39a3ee2• 3 years ago

OK, thanks I don't use C much and definitely forgot about that. But my point still stands doesn't it, in that the author is using these preprocessor macros for general arrays, which don't have a special terminator sentinel.

fefe23• 3 years ago

Why would anyone care what the favorite whatever style of some dude on the Internet is?

I like petunias! Now what? How does that help anyone?

awestroke• 3 years ago

I'll probably copy everything in the post for my next C project. Super nice stuff.

fredrb• 3 years ago

Sharing preferences and opinions on code ergonomics certainly has value for me, and I bet it has to other people too. This is, after all, a developer's forum.

I'm certain your opinion on petunias and your possible distaste for orchids will be welcomed in a flower-news type orange site. :-)

forgotpwd16• 3 years ago

Your preference doesn't help anyone. That's true. But coding styles may improve its reader's programming.

lionkor• 3 years ago

Isn't defining byte = char a bit wrong? char may be signed or unsigned, and may be more or less than 1 byte, right? So why that?

tmtvl3• 3 years ago

char may be signed or unsigned,

Correct, the standard does not specify whether char is signed or unsigned, so it's implementation-specific.

and may be more or less than 1 byte, right?

Wrong, char is specified as a single byte character, so the following will always be true:

  sizeof(char) == 1;

nspattak• 3 years ago

i love this blog, i hold Chris Wellons to a very high estime BUT i utterly disapprove the usage of macros so much, especially to wrap cstd types, functions, etc.

jstimpfle7• 3 years ago

I'm currently on a C++ (mostly C with C++ compiler) trip. It does make some things easier and some things harder. It makes it easier to work with C++ developers :-). I sometimes use the more involved C++ features but often regret it after because of complications.

But one thing that makes it worth it is the removal of the struct tag space. I have a strong dislike for the struct tag boilerplate in C, but the alternative -- typedef boilerplate -- in C is unbearable to the point that I have a macro to define structs in C that does this automatically.

    #define STRUCT(name) typedef struct name name; struct name

    STRUCT(Foo) {
        int x;
        int y;
    };

But macros often come with disadvantages. In this case it's that many IDEs have trouble finding the struct definitions from a usage site.

Luker88• 3 years ago

More than a few of these look like what you will find in Rust by default

Nice to see some evolutive convergence in C programmers, too

neilv• 3 years ago

While I still prefer ALL_CAPS for constants, I’ve adopted lowercase for function-like macros because it’s nicer to read.

"ALL_CAPS" in C was not for constants, but for preprocessor macros. It's shouting in all-caps, because it means "Look out! There's a cpp macro expansion here!"

Related, please stop using "ALL_CAPS" for constants in other languages. Not only does shouting constants as the most prominent syntax in the code make no sense, but there are much better uses for shouting in a programming language.

(For an example of a good use of "ALL_CAPS": if your language ever acquires Scheme-like template-based hygienic macro transformers, "ALL_CAPS" (or "ALL-CAPS") is excellent for making template pattern variables stand out within the otherwise literal code blocks.)

jraph• 3 years ago

Interesting take, but good luck with this fight against all caps (snake case) constants, at this point it's almost a consensus, a shared culture element, a deeply ingrained habit that the vast majority of developers have and recognize.

Changing this would be a huge undertake I'd be afraid of engaging, if I cared that much.

avgcorrection4• 3 years ago

Thanks for bringing this up. There is no reason for modern languages that have proper constants (not preprocessor macros which happen to sometimes be used for them) to use this tedious style.

Constants are so innocent and useful. Why indirectly discourage their use by making their usage an eye-bleed?

barbs• 3 years ago

What alternative would you suggest?

eviks5• 3 years ago

Indeed, these are less readable and harder to type for no benefit

harpiee3• 3 years ago

I do it mainly as a form of namespacing and aid in readability.

  do_thing(foo); // foo is variable

  do_thing(FOO); // FOO is constant (i.e this call should always do the same thing)

  foo = FOO; // I wanna name a variable the same as a constant

swah• 3 years ago

Same, but maybe alternatively I'd accept:

    do_thing(Constants.foo)

as equally clear...

sdk77• 3 years ago

The case of what is a constant, and whether or not it even really is, is not always clear in C. As an embedded developer (almost always on bare metal), variables declared with the const modifier are usually (but not always, it depends on the linker script) placed in read only memory. For those kind of variables (read only ones, they're not really constants as in C++ constexpr) I don't use all caps. But for preprocessor macros, always. Even "#define MY_CONSTANT 10" is a macro, and not a constant or a variable. And it should be treated with caution, because it is dangerous (inexperienced programmers might change it to #define MY_CONST 2 * OTHER_CONSTANT, which opens up a can of worms).

rollcat• 3 years ago

It's the reason Rust makes us use an exclamation mark with macro calls: beware! magic! here!

I like this as a convention, but not necessarily as a grammar rule. Printing values is common enough that it shouldn't require shouting for constant attention, simple code shouldn't trigger sensory overload.

Sharlin2• 3 years ago

I do think that the default convention of SHOUT_CASE for constants in Rust is too in-your-face given that there's nothing about Rust constants that would particularly require them to stand out. I might have gone with CamelCase given that some things in Rust already straddle the "types are CamelCase, terms are snake_case" delineation (enum variants, even data-less ones, are CamelCase, as well as the implicitly defined constant `Foo` for any unit struct `Foo`).

adamrezich• 3 years ago

nah, sorry, I'm going to keep using ALL_CAPS_CONSTANTS (and enum members, because they're also constants). I like having constants be visually distinct from the rest of my code.

P_I_Staker4• 3 years ago

Yeah, I don't see the problem. I believe this is default for pylint, and I see no issue with convention.

bArray• 3 years ago

typedef float f32;
typedef double f64;

Assuming float is 32 bits and double is 64 bits sounds like a foot-gun. OpenCV defines a float16_t [0], CUDA implements half-precision floats [1], micro-controllers implement whatever they want.

C++23 introduces fixed width floating-point types [2], but not aware of any way to enforce this in C. What I would suggest it to have a macro to check data is not lost at compile time.

Generally I agree with others, it might be better to leave some of these things as default for readability, even if it is not concise.

[0] https://docs.opencv.org/4.x/df/dc9/classcv_1_1float16__t.htm...

[1] https://docs.nvidia.com/cuda/cuda-math-api/group__CUDA__MATH...

[2] https://en.cppreference.com/w/cpp/types/floating-point

CodeArtisan• 3 years ago

gcc has _Float<size> types

    typedef _Float32 f32;
    typedef _Float64 f64;

https://gcc.gnu.org/onlinedocs/gcc/Floating-Types.html

sigsev_251• 3 years ago

It's not just gcc, they are in the C23 standard along with the _Decimal<size> types.

thesnide• 3 years ago

comments here are a canonical example of bikeshedding...

jeffrallen• 3 years ago

I came back to C after a good long time in Go, and I found that my C style had picked up some of these same good ideas, which I attributed to Go. In particular I also swore off NUL terminated strings, and started using structure returns to send back multiple values.

moodguy• 3 years ago

For my hobby projects i do the following.

I adopted the style of writing all macros in lower case with the prefix "macro_", so i can grep through all macros. So macro_ becomes like a keyword. Same with enum.

I use almost the same naming scheme for i32,f32, etc., but i typedef for example size_t const to usz, and size_t to usz_ (or use macro mut(x) x ## _) . So all shorter type names are const by default. I use a single header of 35 sloc to do that.

I see that this way of coding can be confusing for other people, so i avoid it when writing code that other people have to work with. But for personal code its really enjoyable for me.

loondri• 3 years ago

I get that everyone has their own coding style, but ditching established conventions in C for personal aesthetic seems a bit much. Like, using u8 or i32 instead of the standard uint8_t or int32_t might save a few keystrokes, but it could confuse anyone else looking at the code. And the custom string type over null-terminated strings? C's built around those, and deviating from that just feels like making life harder for anyone else who might need to work with your code.

And manually writing out Win32 API prototypes instead of including windows.h might shave off some compile time, but it's like ignoring a well-maintained highway to trek through the woods. Just seems like a lot of these changes are about personal preference rather than sticking to what makes C code easy for everyone to work with.

JonChesterfield3• 3 years ago

u16 etc show up a lot and are unlikely to confuse programmers.

Where it does go to pieces is when two different programs both define u16, use them in header files, and then a third program tries to include both those header files at the same time. The big advantage of <stdint.h> is avoiding that failure mode.

The namespaced library type equivalent is something like libname_u32, at which point it's tempting to write uint32_t instead of the libname:: or libname_ prefix.

SkeuomorphicBee• 3 years ago

Like, using u8 or i32 instead of the standard uint8_t or int32_t might save a few keystrokes [...]

It is not about saving keystrokes, it is about reducing sensory load when reading it.

Sorry, I know it may sound like I'm splitting hairs, but every single time when the argument of verbosity vs conciseness in programing languages comes around, this "keystrokes" argument is thrown and it is extremely flawed. The core belief that conciseness is only better for faster typing but that verbosity is somehow always better than conciseness for reading is just plain wrong and we should stop using it. And yes, verbosity has some advantages for reading comprehension, but so does conciseness, no side is a clear winner, it is all about the different compromises.

__loam• 3 years ago

I think you completely missed the point of his comment. C isn't a new programming language. There are well worn conventions and making custom types because you don't like them is like forking your own custom dialect nobody can understand for very little benefit.

michaelcampbell• 3 years ago

Like, using u8 or i32 instead of the standard uint8_t or int32_t might save a few keystrokes, but it could confuse anyone else looking at the code.

This seems a theoretical possibility _at best_, and a fairly strawman-y one at that. I doubt any competent C programmer would get "confused". Irritated at a different style, maybe.

Too, everything is hard to read before you learn to read it. -- Rich Hickey

al_be_back• 3 years ago

> typedef all structures. I used to shy away from it

it seems this may be more an issue with being shy, than a coding issue :P

in my view, language is a Style, so coding in C is c-style coding.

when i started coding in python (small projects initially), my code cried-out Java Java (typing, packaging, naming, oop), and took nearly as long to write - I laughed my head of when I realized, just because I could doesn't mean I should.

JonChesterfield3• 3 years ago

typedef char byte;

That one is dubious. Char has magic aliasing properties that uint8_t might not have (iirc that was contentious in a GCC bug report) and it will be signed on some platforms and unsigned on others, which changes implicit integer conversions.

Missing from this is to embrace attribute((overloadable)) and attribute((cleanup)).

Overloadable is the sane, useful alternative to the thing standardised as _Generic. The C _Generic will let you define an overload set, with some weirdness around type conversions, provided you write the entire set out as a single _Generic expression, probably wrapped in a macro. If you want to dispatch on more than one argument, you nest _Generic expressions. If you want to declare different functions in different headers - maybe you want 'size(T)' defined on various types in the codebase - you can't. If you don't like the idea of thousands of lines of distracting nonsense in the preprocessed output, tough. Or - use overloadable, get open overload sets, minimal compile time cost, obvious intermediate IR, everything works. Prior art is all of C++, so talking decades of the tooling learning to deal with it.

Cleanup is either a replacement for raii, or a means to have debug builds yell at you when you miss a free. It looks like that got warped into a thing called 'defer' with different behaviour that didn't make it through the committee last time.

Other than that, ad hoc code generators work really well with C. Especially if you're willing to use some compiler extensions. Code generators + overloadable will give a fair approximation to templated data structures without going deep into the insanity of the preprocessor. If the overloadable functions are static inline forwarding things in a header they don't even mess up symbol names; you just get a straightforward translation to vector_float_size or whatever.

Personally I've given up on ISO C. I'd quite like to code in a dialect of C99 with a few of the GNU extensions and the equivalent of `fno-strict-aliasing`, but C with the pointer provenance modelling and an accretion of C++ features has no personal value. Currently still using clang with flags to make it behave like that but I'm conscious that's on borrowed time - the application performance friendly aliasing rules are the default and gaining popularity, and relying on opt-out flags is a means of opting into compiler bugs.

Semi-actively seeking something that will let me write assembly without the hassle of manual register allocation and calling conventions. Old style C with some of the warts bashed off would be good for that.

stephc_int134• 3 years ago

One nice thing about short types (i32 f32 u16 etc.) is that they can easily be extended for vector types such as f32x4 or u8x16 etc.

Consistency, conciseness and clarity (you don't have to guess much about those, once you've understood the naming scheme)

Pathogen-David3• 3 years ago

I actually have the opposite feeling. I like the non-sized type names like float extended as float4 or float4x4.

My brain wants to read f32x4 as a 32 by 4 matrix of floats.

(That being said I'd definitely be interested in trying your convention in the context of something like Rust.)

stephc_int134• 3 years ago

float4 is nice, but in video games, especially graphics, the vast majority of our floats are 32 bits but we also use 16 bits floats quite extensively, and in this case it is quite practical to follow the same convention. f32 -> f16 f32x4 -> f16x4

And when working on some heavily optimized SIMD code on the CPU side, I tend to use the default types even less.

uxp8u61q12• 3 years ago

Honest question: why C? I've been writing C++ firmware for SoCs, supposedly an area where C is supposed to be king, and C++ was just as good, except it came with all the batteries included. So, why C?

habibur2• 3 years ago

In my case :

- I prefer functions over classes.

- no mangling of exported names, the binary is re-usable as API.

- in the long term, the C source code is more re-usable in other projects than C++ ones.

and more like this.

kovacs_x• 3 years ago

sure... and what about time spent debugging yet another unallocated/untimely freed/off by 1 pointer mistake?

ps. you know you can write C++ code that is functional and use free functions primarily instead of putting everything in classes?

uxp8u61q12• 3 years ago

I prefer functions over classes.

Then use functions?

no mangling of exported names, the binary is re-usable as API.

Not once in my life have I seen someone use a binary as an API.

in the long term, the C source code is more re-usable in other projects than C++ ones.

I don't even know what you mean by that.

rtz121• 3 years ago

- I prefer functions over classes.

I also prefer apples over brooms.

sebastianz• 3 years ago

it came with all the batteries included

Sometimes you do not want, or need, all the batteries.

uxp8u61q12• 3 years ago

Smart pointers alone make the switch worth it. Why wouldn't you want that?

lelanthran20• 3 years ago

Because the can read someone else C code without needing to look up almost all the quirks they used, while I cannot read someone's C++ code without having Google handy.

Simplicity beats complexity almost every time.

sylware• 3 years ago

I would not use typedefs as this should not be in the C syntax (like enum,switch, and much more).

The primitive type names should be native, but to "fix" C I prefer using the C preprocessor (I use it for namespace/name mangling too). This is not perfect, but should be already way more than enough.

With proper preprocessor usage (without going amok), one can write one compilation unit software roughly easily.

varispeed• 3 years ago

Been there. Writing u8 instead of uint8_t may seem like a time saver, but in reality it makes it more difficult to read and reason about.

If you pack too much information, you are taxing your brain more, you are slower to analyse the code and you make it easier to make mistakes.

Now I much prefer code that is as verbose as possible.

vitiral2• 3 years ago

Great article. One thing for me is that I think we named our variables wrong. We should be specifying the number of bytes, not bits. I use

U1, U2, U4, U8, I1, I2, etc

Also S for "slot" aka unsigned pointer sized integer (usize_t)

Another big point is formatting code to line-up instead of with an autoformatter. When you are doing something which is almost the same but slightly different it helps readability considerably. It is also a sign of a well-loved codebase, since I've never seen an autoformatter that can do it.

Maybe we could make formatters at least auto _detect_ that code is already aligned and to just leave that code alone. Some kind of "love heuristic"

ggliv• 3 years ago

Could you elaborate on the reasoning behind using byte length instead of bit length?

Most of the time when I use fixed-width int types I’m trying to create guarantees for bitwise operators. From my perspective I feel like it therefore makes the most sense to name types on a per-bit level.

vitiral2• 3 years ago

We almost always talk in bytes. When trying to reason about alignment it's bytes, when reading a serial IO from a file it's bytes. I hardly ever think in bits and when I do, I think in hex not decimal.

I also like that it makes all the type names the same width (notably U1/U2 vs u8/u16).

dathinab• 3 years ago

size_t not mapping to size but size being defined is a footgun

I would have used isize instead, I think.

beeforpork2• 3 years ago

Hopefully I never need to review code written with these definitions. It's an awful idea to do this.

The first section shows why some languages have no 'typedef': introducing another layer of aliases is just not a good idea. It's confusing, it changes the appearance to basically a new language. Just use the standard names, instead of redefining your language, like everyone else. This style is almost as bad as '#define begin {'.

Many of the other defs are obfuscations or language changes -- this coerces C to something else. I'd not like to read code written with this, as it heavily violates the principle of least astonishment (POLA).

(As a side note, I don't understand the #define for sizeof. The operator sizeof returns size_t -- it's size_t's definition, so what is this for?)

Pathogen-David3• 3 years ago

As a side note, I don't understand the #define for sizeof.

Their `size` type is signed. It's `ptrdiff_t`, not `size_t`.

beeforpork2• 3 years ago

Ah, thanks! So code will look normal, but be subtly different. This is even worse than I thought!

bullen• 3 years ago

This is my personal style:

http://edit.rupy.se/?host=move.rupy.se&path=/file/game.cpp&s...

It's messy and in many ways ugly but it compiles and runs for an eternity.

monomere• 3 years ago

using namespace std

and then you put the code in a header and everything explodes

gilcot• 3 years ago

When I started reading the first section, about his own types, I couldn't help thinking: oh my, sounds like "Hungarian notation"[1] :)

I think those definitions go to a header file. But how different will it be if he use existing types with an abbreviation system? And is this feature available with some IDE?

[1] https://en.wikipedia.org/wiki/Hungarian_notation

adriangrigore• 3 years ago

Agree on no _t suffixes!

angra_mainyu• 3 years ago

Fascinating how he's incorporated lessons from Go and Rust. The short primitives are definitely a boon for readability and using the s8 type over null-terminated strings is something that should be built in.

omniscient_oce• 3 years ago

Can anyone explain the use of ptrdiff_t instead of size_t (he has typedef'd "size" for ptrdiff_t) The macros are wrapping _Alignof and sizeof both which can't return non-zero numbers I thought.

bergkvist• 3 years ago

ptrdiff_t is a signed integer type - which means you can subtract these numbers without worrying about underflow

saw-lau• 3 years ago

I love some of the ideas here! Particularly the neat string 'class' and hand-defining Windows API functions instead of dragging in Windows.h.

There's clearly life in the old dog yet!

My personal C coding style as of late 2023

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