C Gibberish to English

48 points by warkanlock 3 days ago | 34 comments

   char (*(*x[3])())[5]

I'm more of the mindset that writing something like this is probably a code smell to begin with. Is there any reason I'm not thinking of right now, that this couldn't be typedef'd and refactored into something far more readable?

C gets a lot of blame for pointer gibberish like this but quite honestly you can write gibberish in any language. I don't see any fundamental or technical reason you couldn't write clean, readable C.

26 minutes ago | root | parent | next |

[deleted]

jacoblambda 20 minutes ago | root | parent | prev |

the function signature certainly should be type def-ed. i.e.

    typedef char (*fn())[5];

and then you have the original as

    fn x [3];

pavlov 5 hours ago | prev | next |

Use typedef?

Granted, the function pointer syntax is forever confusing (to me anyway). The rest is easily tackled by naming things.

Even for function pointers, it’s just one lookup and then you can copy-paste the typedef for any other function pointer types in the project.

khrbtxyz 2 hours ago | root | parent | next |

Function typedefs make this less confusing by removing awkward parentheses. e.g.

  typedef int read_block_fn(void *context, u8 *buf, unsigned int block, size_t len);

https://github.com/torvalds/linux/blob/0a9b9d17f3a781dea03ba...

Reading C Type Declarations: http://unixwiz.net/techtips/reading-cdecl.html

(NOT the author. It simply helped me.)

sebstefan 5 hours ago | root | parent | prev |

>Use typedef?

What if you're given somebody else's code and you need to understand it to put a typedef there

jacoblambda 13 minutes ago | root | parent | next |

The trick is to just assert equal types. Most compilers have extensions that allow you to easily compare type equality (and C23 actually standardizes the `typeof()` operator).

So you basically take your ugly type, put it in a #define and then create a static assertion that matches the type against said ugly type.

Now the compiler will throw a shit fit if the types don't match. Have fun breaking the type up into smaller pieces until you have something legible.

DaiPlusPlus 4 hours ago | root | parent | prev |

Welp, if it’s that bad then shrug and use a #define

(Yes, this is a joke)

elcritch 3 hours ago | prev | next |

Handy site!

Next I want one to explain some of Rust’s more cryptic pointer gibberish. Usually I just hit “use suggested fix X” until the compiler’s happy.

Thiez an hour ago | root | parent |

Rust isn't so bad, is it? The example of `char ((x[3])())[5]` would translate to `[fn() -> [fn() -> u8; 5]; 3]`. It's inherently an ugly type, but I think it's easier to read than the C version.

card_zero 5 hours ago | prev | next |

Is there a language that's substantially free of gibberish?

chongli 3 hours ago | root | parent | next |

Racket Beginning Student [1] language.

[1] https://docs.racket-lang.org/htdp-langs/beginner.html

Those of Algol/Wirth linage, or influenced by then.

Then again people complain that they are too verbose, and they rather write in hieroglyph friendly languages.

Joker_vD 3 hours ago | root | parent |

Compare

   char (*(*x())[5])();

and

   var x: pointer to func() pointer to array[5] of pointer to func() char;

or if you wish to replace some keywords with glyphs:

   var x: ^func() ^[5] ^func() char;

And it's always a nice puzzle for the reader to explain why there are three "pointer" in cdecl output and three carets in the ALGOL-like declaration, but only two asterisks in the C declaration.

trealira 3 hours ago | root | parent |

In this case, the C declaration doesn't match the other two. The variable x is a function that returns a pointer to an array of 5 pointers to functions returning char. Indeed, that's what cdecl.org says:

  declare x as function returning pointer to array 5 of pointer to function returning char

Using the notation you did, that would be:

  var x: func() ^[5] ^func() char

There are only two arrows there now.

If you wanted a pointer to a function like this, you would need a third asterisk in the declaration:

  char (*(*(*x)())[5])();

Joker_vD 2 hours ago | root | parent |

Oh, good catch, thank you! But I remember an example with some other tricky C expression/type declarator where the number of actual dereferences differed from the amount of asterisks in the code.

> Using the notation you did, that would be:

Well, it'd be

    func x() ^[5] ^func() char; ...

because it's a function declaration, after all, not a variable.

for declaring function pointer?

Any language with type after name :

    // c
    char (*(*x[3])())[5];
    // golang
    var x [3]func() *[5]byte

Depends on the features you want.

Yeah sure, COBOL is great in that regard. Basically reads as English.

pwilson7 3 hours ago | root | parent | prev |

nope

makach 3 hours ago | prev | next |

I can read that.

I don't think it is gibberish. It's code and in order to read that code you need to understand the language, and to understand language you need learning and experience.

Maybe it can be useful for learning, but if you have to use such tool, I suspect you won't understand it anyway - so in a way it is more a gibberish-to-gibberish translator.

tuveson an hour ago | root | parent |

I disagree. The conventions for declaring arrays, pointers, and function pointers are all idiosyncratic. In C, the type is always to the left of the variable being declared. Except for arrays, which have part of the declaration to the right. And except for pointers, which need to be affixed to every item if there are multiple declarations. And except for function pointers where you need to wrap the variable name like (*name). Individually I can wrap my head around these exceptions, but putting all of them together, it's just hard to read.

djmips 5 hours ago | prev | next |

Is this largely supplanted by LLMs?

veltas 4 hours ago | root | parent | next |

The difference is I trust this website, and wouldn't trust an LLM.

LLMs are mostly correct with regards to this stuff.

cdecl is always correct with regards to this stuff.

I don't know why you'd choose the former.

Y_Y 3 hours ago | root | parent |

Because if you don't do things exactly the way cdecl wants you get a Syntax Error

marginalia_nu an hour ago | root | parent |

Wouldn't any explanation given, apart from syntax error, be wrong in the case you provide it with an invalid syntax?

Y_Y 32 minutes ago | root | parent |

I was thinking of the issue of going from English to C. Even when you out in malformed C it's nice to get either a compiler error which explains the problem, or even better an LLM that can suggest how to fix it.

andix 4 hours ago | root | parent | prev |

Probably.

Output for the example I got on opening the website:

  char (*(*x())[5])()

cdecl.org: declare x as function returning pointer to array 5 of pointer to function returning char

ChatGPT: x is a function that, when called, gives us access to 5 functions that each return a character. (TL;DR, it gave a full explanation too)

Like mentioned before the error rate of LLMs is probably much higher on complex expressions.

ngcc_hk 2 days ago | prev | next |

May need some bracket first then English.

lynx23 5 hours ago | prev | next |

Why is it that the first thing I try tends to uncover shortcomings?

typedef uint64_t qbb_t __attribute__((vector_size(sizeof(uint64_t) * 4)))

Syntax error

OK, its an extension, meh.

veltas 4 hours ago | root | parent |

Looking at the project issues, it seems it supports only 1989-era C, and some Apple stuff, before you even get to attributes.

dangsux 5 hours ago | prev |

[dead]