Re: [PATCH v1 1/2] [troff]: Add lengthof() macro.

[Alejandro Colomar]

Hi Lennart,

On 2023-08-27 02:00, Alejandro Colomar wrote:
> Hi Lennart, Branden,
> 
> On 2023-08-26 21:36, Lennart Jablonka wrote:
>> Quoth Alejandro Colomar:
>>> The good news is that I like the implementation.  I just don't like the
>>> name.  I have a sizeof_array() macro that does
>>>
>>> #define sizeof_array(a)  (sizeof(a) + must_be_array(a))
>>>
>>> That is, it calculates the size in bytes that the array takes up in memory.
>>>
>>> <https://github.com/shadow-maint/shadow/pull/762/commits/8d06d849dcb5f7041e048d866ec7ce6c1853245b>
>>>
>>> For a macro that returns the number of elements in an array, I'd like a
>>> name that cannot be confused with that at all.  NELEMS(), NITEMS(),
>>> array_count(), or lengthof() all seem better than array_size().
>>>
>>> I'm not a fan of lengthof(), even if it's a proposal to ISO C, as so far
>>> the term "length" was only the number of non-zero characters in a string,
>>> and overloading it to mean the number of elements in an array would
>>> similarly be a bad thing.  At least it's not so confusing as size, though.
>>>
>>> NITEMS() or NELEMS() seems the best choice to me.
>>
>> I like both lengthof (as “length” is commonly used for the number 
>> of elements in an array) and nelem (which is what Plan 9 uses).   
>> I do wanna note that the term used by the C standard is “size” and 
>> the term used by the C++ standard is “bound.”   How about boundof?
> 
> A quotation of ISO C would be interesting here.  Preferably C17.
> 
> I certainly remember ISO C talking about the number of elements in an
> array.  While I wouldn't be surprised to learn that it uses the term
> 'size' when it's being more specific, I don't recall it from the top
> of my head.


Self correction:  it talks about elements in an array, but not necessarily
about the number of it.

And here's a quote where ISO C says that the size of an array is the
value delimited by []: <https://port70.net/%7Ensz/c/c11/n1570.html#6.7.6.2p1>

Confusingly enough, when it talks about sizeof(), it let's you think that
the size of an array could also mean its size in bytes.  ISO C should
probably reword one of those.

<https://port70.net/%7Ensz/c/c11/n1570.html#6.5.3.4p2>

Cheers,
Alex

-- 
<http://www.alejandro-colomar.es/>
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