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Re: C String terminator

Path csiph.com!eternal-september.org!feeder.eternal-september.org!reader01.eternal-september.org!.POSTED!not-for-mail
From Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups comp.lang.c
Subject Re: C String terminator
Date Fri, 27 Mar 2020 23:26:30 -0700
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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:
>> [...]
>>
>>>>> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>>>>
>>>> [...]
>>>>
>>>>>> A pointer to a string *is* required for a "%s" directive, but the
>>>>>> standard says so only indirectly.
>>
>> [...]
>>
>>> I need to add though that 'char' is not really accurate.  The Standard
>>> says "character type" and I think it means that, not just 'char'.

You're right.  (Note that that was in response to text that was later
snipped.)  Still, I believe "pointer to a string" is correct, though the
elements of a string may be of type char, signed char, or unsigned char.
(It's possible the standard's definition of "character" leaves some
additional wiggle room.)

>>> Furthermore if an 'l' length modifier is present then the array
>>> elements are assumed to be of type 'wchar_t'.  Both the regular
>>> character types and wchar_t fall under the common umbrella of
>>> "character type".
>>
>> When I wrote "%s" directive, I meant "%s" directive.
>
> Sorry, I thought we were talking about things the Standard
> actually discusses.

I don't know (and I'm not asking) why you thought that.  If I were
talking about "things the Standard actually discusses", I wouldn't
have written "... but the standard says so only indirectly".

>                      The Standard makes no statements about
> '"%s" directives', unless you want to count examples that
> happen to have a %s as part of a format string.

My statement was precisely about a directive consisting only of
the character sequence "%s".  If by 'a "%s" directive' I had meant
"a directive containing an 's' conversion specifier" you could
have rightly criticized me for being imprecise.  I observed, as a
mildly interesting point, that the requirements for the argument
corresponding to a "%s" specifier are equivalent to requiring a
pointer to a string, though the standard doesn't state it in those
terms (and I do not suggest that it should).

Regarding a point I raised above, 3.7.1 defines a "character"
as a "bit representation that fits in a byte", and 7.1.1 defines
a "string" as a sequence of characters -- but "%s" specifically
requires a pointer to the initial element of an array of character
type, i.e., one of char, signed char, or unsigned char.  I see
no requirement that a "character" must be of "character type".
Possibly the standard's definition of "character" is incomplete
and/or does not fully convey the intent.

An implementation could have an extended integer type (say, "_Byte")
with a size of 1 byte that is not a character type.  A pointer value
of type _Byte* might meet the definition of "a pointer to a string",
but would not be valid as an argument corresponding to "%s".  I doubt
that this is relevant for any real-world implementation, but my
original statement might not be correct for all possible conforming
implementations, assuming we take the standard's definitions literally.
Single-byte enums might also raise some issues (they could be
*compatible* with a character type without *being* a character type).

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips Healthcare
void Void(void) { Void(); } /* The recursive call of the void */

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Re: C String terminator Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 02:25 -0800
  Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-16 14:24 -0800
    Re: C String terminator Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 08:13 -0800
      Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-22 09:05 -0800
        Re: C String terminator Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-03-27 19:58 -0700
          Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-27 23:26 -0700
            Re: C String terminator Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 09:21 -0700
              Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-02 09:54 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-02 11:17 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-02 13:12 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-02 13:28 -0700
                Re: C String terminator Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 19:17 -0700
                Re: C String terminator David Brown <david.brown@hesbynett.no> - 2020-04-03 09:47 +0200
                Re: C String terminator already5chosen@yahoo.com - 2020-04-03 08:03 -0700
                Re: C String terminator David Brown <david.brown@hesbynett.no> - 2020-04-03 17:34 +0200
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-03 12:39 -0400
                Re: C String terminator Bart <bc@freeuk.com> - 2020-04-03 18:05 +0100
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-03 10:18 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-03 22:13 +0100
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-03 14:36 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-03 16:18 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-04 01:43 -0700
                Re: C String terminator David Brown <david.brown@hesbynett.no> - 2020-04-04 18:23 +0200
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-04 11:18 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-04 13:02 -0700
                Re: C String terminator David Brown <david.brown@hesbynett.no> - 2020-04-05 21:54 +0200
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-05 13:59 -0700
                Re: C String terminator David Brown <david.brown@hesbynett.no> - 2020-04-06 09:07 +0200
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-06 02:25 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-06 11:43 +0100
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-06 03:56 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-06 16:34 +0100
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-06 10:30 -0700
                Re: C String terminator richard@cogsci.ed.ac.uk (Richard Tobin) - 2020-04-06 17:50 +0000
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-06 11:31 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-06 12:04 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-06 21:51 +0100
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-06 14:34 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-06 14:39 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-06 14:52 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-06 15:31 -0700
                Re: C String terminator jameskuyper@stellarscience.com - 2020-04-06 16:05 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-07 03:08 +0100
                Re: C String terminator Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2020-04-06 21:12 -0600
                Re: C String terminator scott@slp53.sl.home (Scott Lurndal) - 2020-04-07 16:55 +0000
                Re: C String terminator Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2020-04-07 11:05 -0600
                Re: C String terminator David Brown <david.brown@hesbynett.no> - 2020-04-07 20:39 +0200
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-07 11:48 -0700
                Re: C String terminator Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2020-04-07 21:21 -0600
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-07 20:40 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-08 01:41 -0700
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-08 07:40 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-08 08:16 -0700
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-08 09:17 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-08 09:46 -0700
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-08 10:37 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-08 10:48 -0700
                Re: C String terminator Richard Damon <Richard@Damon-Family.org> - 2020-04-08 14:07 -0400
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-08 11:29 -0700
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-08 16:46 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-09 01:57 -0700
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-09 08:42 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-09 08:56 -0700
                Re: C String terminator Richard Damon <Richard@Damon-Family.org> - 2020-04-09 12:42 -0400
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-09 10:12 -0700
                Re: C String terminator Richard Damon <Richard@Damon-Family.org> - 2020-04-09 15:51 -0400
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-09 13:02 -0700
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-09 13:06 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-09 14:49 -0700
                Re: C String terminator Richard Damon <Richard@Damon-Family.org> - 2020-04-09 19:05 -0400
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-10 02:25 -0700
                Re: C String terminator Öö Tiib <ootiib@hot.ee> - 2020-04-10 04:38 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-10 05:21 -0700
                Re: C String terminator Öö Tiib <ootiib@hot.ee> - 2020-04-10 07:13 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-10 11:38 -0700
                Re: C String terminator Ike Naar <ike@sdf.lonestar.org> - 2020-04-11 17:38 +0000
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-11 15:04 -0700
                Re: C String terminator Richard Damon <Richard@Damon-Family.org> - 2020-04-11 15:16 -0400
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-11 21:45 +0100
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-12 04:39 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-12 21:34 +0100
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-12 14:38 -0700
                Re: C String terminator Richard Damon <Richard@Damon-Family.org> - 2020-04-13 11:13 -0400
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-13 08:24 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-11 15:08 -0700
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-09 09:53 -0700
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-07 14:35 -0400
                Re: C String terminator Öö Tiib <ootiib@hot.ee> - 2020-04-06 21:04 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-07 01:16 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-07 02:08 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-07 02:19 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-07 08:42 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-07 10:39 -0700
                Re: C String terminator scott@slp53.sl.home (Scott Lurndal) - 2020-04-07 17:45 +0000
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-07 14:40 -0400
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-07 11:03 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-07 11:14 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-07 12:19 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-07 12:02 +0100
                Re: C String terminator Öö Tiib <ootiib@hot.ee> - 2020-04-07 06:27 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-07 07:44 -0700
                Re: C String terminator Öö Tiib <ootiib@hot.ee> - 2020-04-07 08:30 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-07 00:27 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-07 12:50 +0100
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-07 05:25 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-07 23:52 +0100
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-08 03:15 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-08 21:28 +0100
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-08 15:40 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-09 00:31 +0100
                Re: C String terminator Ike Naar <ike@sdf.lonestar.org> - 2020-04-07 21:40 +0000
                Re: C String terminator luser droog <luser.droog@gmail.com> - 2020-04-06 09:41 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-06 12:46 -0700
                Re: C String terminator Guillaume <message@bottle.org> - 2020-04-07 17:17 +0200
                Re: C String terminator Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-09 07:23 -0700
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-04 22:32 +0100
                Re: C String terminator David Brown <david.brown@hesbynett.no> - 2020-04-03 21:59 +0200
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-03 23:48 -0400
                Jared Kushner would be proud... (Was: C String terminator) gazelle@shell.xmission.com (Kenny McCormack) - 2020-04-04 09:00 +0000
                Re: Jared Kushner would be proud... (Was: C String terminator) Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-04 02:45 -0700
                Re: Jared Kushner would be proud... (Was: C String terminator) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-04-04 10:24 +0000
                Re: Jared Kushner would be proud... (Was: C String terminator) Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-04 03:55 -0700
                Re: Jared Kushner would be proud... Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-04 13:27 -0700
                Re: Jared Kushner would be proud... Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-04 13:52 -0700
                Re: Jared Kushner would be proud... Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-04 14:12 -0700
                Re: Jared Kushner would be proud... Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-04 15:12 -0700
                Re: Jared Kushner would be proud... Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-04 15:03 -0700
                Re: Jared Kushner would be proud... Richard Damon <Richard@Damon-Family.org> - 2020-04-04 18:46 -0400
                Re: Jared Kushner would be proud... Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-05 01:53 -0700
                Re: Jared Kushner would be proud... Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-05 02:33 -0700
                Re: Jared Kushner would be proud... Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-05 06:43 -0700
                Re: Jared Kushner would be proud... (Was: C String terminator) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-04 19:48 -0700
                Re: Jared Kushner would be proud... (Was: C String terminator) James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-04 06:37 -0700
                Re: C String terminator David Brown <david.brown@hesbynett.no> - 2020-04-04 18:36 +0200
                Re: C String terminator dave_thompson_2@comcast.net - 2020-05-02 15:13 -0400
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-03 09:41 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-03 10:33 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-03 11:14 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-03 11:34 -0700
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-03 14:48 -0400
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-03 12:10 -0700
                Re: C String terminator Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-03 13:24 -0700
                Re: C String terminator James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-03 23:59 -0400
                Re: C String terminator Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-03 22:05 +0100
                Re: C String terminator Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-04 20:34 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-05 02:05 -0700
                Re: C String terminator Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-09 07:35 -0700
                Re: C String terminator Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-09 07:38 -0700

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