Path: csiph.com!eternal-september.org!feeder.eternal-september.org!nntp.eternal-september.org!.POSTED!not-for-mail
From: Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: Why is this happening?
Date: Mon, 06 Apr 2026 14:20:26 -0700
Organization: None to speak of
Lines: 75
Message-ID: <877bqj4wh1.fsf@example.invalid>
References: <10q5046$3ec1o$2@dont-email.me> <10q523v$3e865$1@dont-email.me> <n2n05bFmg8nU2@mid.individual.net> <10q7bug$7vod$1@dont-email.me> <87bjg8wrgl.fsf@example.invalid> <CfSxR.24256$eG1.15763@fx33.iad> <86bjg72xl6.fsf@linuxsc.com> <87zf3rurp9.fsf@example.invalid> <86ldezzyx1.fsf@linuxsc.com>
MIME-Version: 1.0
Content-Type: text/plain
Injection-Date: Mon, 06 Apr 2026 21:20:27 +0000 (UTC)
Injection-Info: dont-email.me; posting-host="c89d67d6d7dc44c8a8f559dd5aa96ee5"; logging-data="2523272"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1/RsEkQTYgPwQ1yNA7oQ0IT"
User-Agent: Gnus/5.13 (Gnus v5.13)
Cancel-Lock: sha1:qW+Q2epvCYUOoJW1/L5bRMfcoSY= sha1:ZYThn2S58LPaEfa6O7kYr3nXkEQ=
Xref: csiph.com comp.lang.c:397392

Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>> scott@slp53.sl.home (Scott Lurndal) writes:
>>>> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>>>>> Lawrence D <<E2>> ??Oliveiro <ldo@nz.invalid> writes:
>>>>>> On Fri, 27 Mar 2026 10:15:23 +0100, Josef M@C3{B6}llers wrote:
>>>>>>>      diffns += 1000000000UL;
>>>>>>
>>>>>> Can you write
>>>>>>
>>>>>>       diffns += 1_000_000_000UL;
>>>>>>
>>>>>> yet?
>>>>>
>>>>> Not in C.  C23 introduces the apostrophe as a digit separator, copied
>>>>> from C++:
>>>>>
>>>>>      diffns += 1'000'000'000UL;
>>>>
>>>> Or diffns += 1000ul * 1000ul * 1000ul;
>>>>
>>>> or diffns += 1 * NS_PER_SEC;
>>>>
>>>> with
>>>> #define NS_PER_SEC ((1000ul * 1000ul * 1000ul))
>>>>
>>>>> (I would have preferred underscores, but that would have conflicted
>>>>> with C++'s user-defined literals.)
>>>>
>>>> Likewise, I'd prefer the underscore.
>>>
>>> Ditto.  And there is no reason C could have allowed both,
>>> and C++ be damned.
>>
>> (I think you omitted a "not".)
>
> Yes, as I explained in a followup to myself.
>
>> Using apostrophes is IMHO far better than either allowing two
>> arbitrarily distinct syntaxes or a gratuitous incompatibility
>> with C++.
>
> One, it is not an incompatibility.  It's an upward compatible
> extension.

Your proposal, I think, is for C to permit both apostrophes and
underscores as digit separators.  I suppose that's not strictly an
"incompatibility", but it would mean that any code intended to be
compiled as either C or C++ cannot use underscores.

Your "C++ be damned" attitude is not shared by either language
committee (fortunately, IMHO).

> Two, it's not gratuitous.  The extension is proposed because it
> provides a positive value, and I'm not the only one who thinks
> so.

I disagree.  I've already said that I would have preferred
underscores over apostrophes, but both languages now use apostrophes.
If C allowed both, there would be no firm basis for deciding which
to use.  It would make the language slightly more complicated,
with no real benefit than I can see.  The only thing I can think of
that might be a "positive value" is that *some* programmers would
be able to use a symbol that they think looks better.

It would be similar to allowing programmers to use "begin" and "end"
rather than "{" and "}".  I'm sure some programmers would like that,
but the result would be a mess.

What positive value do you think permitting underscores would add?

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */