Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: dollar sign in variable name |
| Date | 2015-11-20 03:32 -0800 |
| Organization | None to speak of |
| Message-ID | <lna8q8ewjh.fsf@kst-u.example.com> (permalink) |
| References | <de259813-bcaf-4334-9fa8-a2cfff5d2251@googlegroups.com> <n2lpf3$aiu$1@dont-email.me> |
Richard Heathfield <rjh@cpax.org.uk> writes:
> On 20/11/15 00:18, Jay Braun wrote:
>> I was just playing around in gcc, and named a variable game$time, and
>> a function set_game$time, and the compiler accepted it. The small
>> program linked and ran fine as well. This required no special
>> options.
>>
>> Would I be playing with fire if I used dollar signs in identifiers?
>
> Not if you're happy for your code only to be compilable with gcc, no.
>
> Such things are called "extensions". Any compiler writer can offer
> extensions as long as they don't interfere with what is often called
> "legal" C code. Dollar signs don't interfere (because they're
> "illegal"), so no "legal" C program can include them, and so allowing
> them cannot break any "legal" C program, so it's fine. But don't expect
> it to work when compiled by implementations other than gcc.
Strictly speaking, it's not an extension in the sense used in N1570 4p6.
If it were, a diagnostic would still be required when the compiler is
invoked in conforming mode.
6.4.2.1, which defines the syntax of identifiers, permits "other
implementation-defined characters". That wasn't the case in C90.
(Which is why "gcc -std=c90 -pedantic" warns about it, but
"gcc -std=c99 -pedantic" doesn't.)
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
dollar sign in variable name Jay Braun <lyngwyst@gmail.com> - 2015-11-19 16:18 -0800
Re: dollar sign in variable name BartC <bc@freeuk.com> - 2015-11-20 00:27 +0000
Re: dollar sign in variable name Jay Braun <lyngwyst@gmail.com> - 2015-11-19 16:29 -0800
Re: dollar sign in variable name Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-11-19 20:05 -0700
Re: dollar sign in variable name Richard Heathfield <rjh@cpax.org.uk> - 2015-11-20 00:30 +0000
Re: dollar sign in variable name Jay Braun <lyngwyst@gmail.com> - 2015-11-19 16:37 -0800
Re: dollar sign in variable name Ian Collins <ian-news@hotmail.com> - 2015-11-20 13:42 +1300
Re: dollar sign in variable name BartC <bc@freeuk.com> - 2015-11-20 00:47 +0000
Re: dollar sign in variable name Philipp Klaus Krause <pkk@spth.de> - 2015-11-21 17:24 +0100
Re: dollar sign in variable name Philip Lantz <prl@canterey.us> - 2015-11-22 15:37 -0800
Re: dollar sign in variable name Robert Wessel <robertwessel2@yahoo.com> - 2015-11-19 23:22 -0600
Re: dollar sign in variable name glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-20 06:51 +0000
Re: dollar sign in variable name Keith Thompson <kst-u@mib.org> - 2015-11-20 03:32 -0800
Re: dollar sign in variable name Ken Brody <kenbrody@spamcop.net> - 2015-11-23 13:27 -0500
Re: dollar sign in variable name Barry Schwarz <schwarzb@dqel.com> - 2015-11-19 16:41 -0800
Re: dollar sign in variable name glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-20 00:53 +0000
Re: dollar sign in variable name Geoff <geoff@invalid.invalid> - 2015-11-19 21:40 -0800
Re: dollar sign in variable name David Brown <david.brown@hesbynett.no> - 2015-11-20 11:04 +0100
Re: dollar sign in variable name Jay Braun <lyngwyst@gmail.com> - 2015-11-20 06:35 -0800
csiph-web