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Re: Comma operator in for() statements

Subject Re: Comma operator in for() statements
Newsgroups comp.lang.c
References <m9kd7f94epq2eumphiui7gf2ubc6p8ah8e@4ax.com> <1NIdG.90366$0hk.19720@fx08.am4> <0fc029c2-7036-4ca9-86af-15913f874a08@googlegroups.com> <20200324202535.68c64bb9be8f95153b947f4b@g{oogle}mail.com> <r5e70s$f7u$1@dont-email.me>
From Bart <bc@freeuk.com>
Message-ID <E%yeG.7798$SW6.537@fx13.am4> (permalink)
Organization virginmedia.com
Date 2020-03-25 02:05 +0000

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On 25/03/2020 00:01, James Kuyper wrote:
> On 3/24/20 1:25 PM, Anton Shepelev wrote:
>> James Kuyper to Bart:
>>
>>>> Most C coders here would still see that as for-loop.
>>>>
>>>> I see it as just a while loop:
>>>>
>>>>       count = 0;
>>>>       ent = master;
>>>>
>>>>       while (ent) {
>>>>           ++count;
>>>>           ent = ent->chain;
>>>>       }
>>>>
>>> All C coders see it as a for-loop. You have very strong
>>> preferences for a language significantly different than C,
>>> and let those preferences interfere with your ability to
>>> understand what C actually is. As a result, you're not
>>> really a C coder, just someone who writes C code without
>>> properly understanding it.
>>
>> I see it as a while-loop, too, so count me with Bart.  My
> 
> Seeing it as a while statement requires ignoring the C syntax: while
> statements start with the "while" keyword. Statements that start with
> the "for" keyword are for statements, not while statements. I'm pointing
> out the obvious, not because I think you don't know the difference, but
> because I think it's stupid to using working that implies that it isn't
> a difference.
> 
> Seeing it as equivalent to a compound statement that includes the
> initializer followed by a while statement is quite reasonable - with the
> exception of the way the continue statement is handled, the two are
> quite similar. C90 actually described the for-statement that way (except
> for the compound-statement part, which wasn't needed in C90).
> Starting with C99, the for loop's description is independent of the
> while statement's description, but the meaning is essentially unchanged,
> other than the fact that it is now permissible to declare identifiers in
> the first section of a for statement.
> 
> However, expressing that equivalence by saying that a for-statement IS a
> while-statement is just plain stupid. Among other things, it ignores the
> initializer.
> 
It is the task that is being done that is seen as a while-loop. Although 
that task is not easy to identify in for-loop form.

I think I would be less critical of C's for-loop if it was instead 
written like this:

    while (int i=0; i<N; ++i) {...}

With 2 of the expressions optional leaving only the middle one for a 
regular while-loop.

Then 'for' can be reserved for ordinary iteration with an official index 
variable.

It would mean I could instantly identify these main classes of loop:

   while (B) ...         Regular while loop

   for (i, A, B) ....    Will always be iteration (may need to be A..B-1
                         for C language)

   while (A; B; C) ...   Warning bells sound ...

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Thread

Comma operator in for() statements Geoff <geoff@invalid.invalid> - 2020-03-21 19:51 -0700
  Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-22 03:31 +0000
    Re: Comma operator in for() statements Geoff <geoff@invalid.invalid> - 2020-03-21 23:17 -0700
      Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-22 12:00 +0000
        Re: Comma operator in for() statements Geoff <geoff@invalid.invalid> - 2020-03-22 08:57 -0700
          Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-22 16:20 +0000
            Re: Comma operator in for() statements Geoff <geoff@invalid.invalid> - 2020-03-22 14:02 -0700
              Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-22 21:26 +0000
    Re: Comma operator in for() statements David Brown <david.brown@hesbynett.no> - 2020-03-22 10:25 +0100
    Re: Comma operator in for() statements Richard Damon <Richard@Damon-Family.org> - 2020-03-22 08:27 -0400
      Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-22 16:31 +0000
  Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-22 00:33 -0400
  Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-22 12:23 +0000
    Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-22 05:47 -0700
      Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-22 14:17 +0000
        Re: Comma operator in for() statements felix@palmen-it.de (Felix Palmen) - 2020-03-22 15:55 +0100
          Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-22 15:01 +0000
            Re: Comma operator in for() statements felix@palmen-it.de (Felix Palmen) - 2020-03-22 16:05 +0100
              Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-22 16:46 +0000
                Re: Comma operator in for() statements felix@palmen-it.de (Felix Palmen) - 2020-03-22 18:14 +0100
                Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-22 11:42 -0700
                Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-22 22:03 +0000
                Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-22 23:51 -0700
                Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-23 14:37 +0000
                Re: Comma operator in for() statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-03-23 08:41 -0700
                Re: Comma operator in for() statements Guillaume <message@bottle.org> - 2020-03-23 16:53 +0100
                Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-23 16:31 +0000
                Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-23 16:48 +0000
                Re: Comma operator in for() statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-03-23 09:53 -0700
                Re: Comma operator in for() statements David Brown <david.brown@hesbynett.no> - 2020-03-23 18:59 +0100
                Re: Comma operator in for() statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-03-23 11:23 -0700
                Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-23 19:51 +0000
                Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-23 14:28 -0700
                Re: Comma operator in for() statements Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-23 13:09 -0700
                Re: Comma operator in for() statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-03-23 13:20 -0700
                Re: Comma operator in for() statements scott@slp53.sl.home (Scott Lurndal) - 2020-03-23 20:26 +0000
                Re: Comma operator in for() statements Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-23 13:55 -0700
                Re: Comma operator in for() statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-03-23 15:43 -0700
                Re: Comma operator in for() statements Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-23 16:27 -0700
                Re: Comma operator in for() statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-03-23 17:13 -0700
                Re: Comma operator in for() statements Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-23 21:11 -0700
                Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-24 00:19 +0000
                Re: Comma operator in for() statements David Brown <david.brown@hesbynett.no> - 2020-03-24 10:30 +0100
                Re: Comma operator in for() statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-03-24 03:07 -0700
                Re: Comma operator in for() statements David Brown <david.brown@hesbynett.no> - 2020-03-24 11:37 +0100
                Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-24 11:18 +0000
                Re: Comma operator in for() statements David Brown <david.brown@hesbynett.no> - 2020-03-24 13:23 +0100
                Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-24 14:53 +0000
                Re: Comma operator in for() statements David Brown <david.brown@hesbynett.no> - 2020-03-25 10:35 +0100
                Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-25 11:12 +0000
                Re: Comma operator in for() statements Ike Naar <ike@sdf.lonestar.org> - 2020-03-26 19:21 +0000
                Re: Comma operator in for() statements luser droog <luser.droog@gmail.com> - 2020-03-24 21:22 -0700
                Re: Comma operator in for() statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-03-27 06:46 -0700
                Re: Comma operator in for() statements luser droog <luser.droog@gmail.com> - 2020-03-28 01:01 -0700
                Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-28 11:26 +0000
                Re: Comma operator in for() statements luser droog <luser.droog@gmail.com> - 2020-03-28 14:22 -0700
                Re: Comma operator in for() statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 08:12 -0700
                Re: Comma operator in for() statements luser droog <luser.droog@gmail.com> - 2020-04-02 12:21 -0700
                Re: Comma operator in for() statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 19:43 -0700
                Re: Comma operator in for() statements Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-24 12:56 -0700
                Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-24 23:44 +0000
                Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-23 17:10 -0700
                Re: Comma operator in for() statements David Brown <david.brown@hesbynett.no> - 2020-03-24 10:17 +0100
                Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-23 18:13 +0000
                Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-23 09:32 -0700
                Re: Comma operator in for() statements David Brown <david.brown@hesbynett.no> - 2020-03-23 19:06 +0100
                Re: Comma operator in for() statements Richard Damon <Richard@Damon-Family.org> - 2020-03-23 13:23 -0400
                Re: Comma operator in for() statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-03-23 10:33 -0700
                Re: Comma operator in for() statements Guillaume <message@bottle.org> - 2020-03-23 18:34 +0100
                Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-23 18:18 +0000
                Re: Comma operator in for() statements Ike Naar <ike@sdf.lonestar.org> - 2020-03-23 22:29 +0000
                Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-23 23:13 +0000
            Re: Comma operator in for() statements richard@cogsci.ed.ac.uk (Richard Tobin) - 2020-03-22 15:17 +0000
          Re: Comma operator in for() statements nobody@example.org (Scott) - 2020-03-22 16:16 +0000
            Re: Comma operator in for() statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-03-23 07:22 -0700
            Re: Comma operator in for() statements Guillaume <message@bottle.org> - 2020-03-25 15:10 +0100
              Re: Comma operator in for() statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-03-25 15:18 +0000
          Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-22 16:27 +0000
          Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-22 15:07 -0400
        Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-22 11:33 -0700
      Re: Comma operator in for() statements Anton Shepelev <anton.txt@g{oogle}mail.com> - 2020-03-24 20:25 +0300
        Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-24 23:25 +0000
          Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-25 01:55 +0000
            Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-25 11:01 +0000
          Re: Comma operator in for() statements Anton Shepelev <anton.txt@g{oogle}mail.com> - 2020-03-25 14:59 +0300
            Re: Comma operator in for() statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-03-27 07:42 -0700
              Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-27 14:51 +0000
                Re: Comma operator in for() statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 19:20 -0700
        Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-24 20:01 -0400
          Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-25 02:05 +0000
            Re: Comma operator in for() statements Bart <bc@freeuk.com> - 2020-03-25 15:13 +0000
          Re: Comma operator in for() statements Anton Shepelev <anton.txt@g{oogle}mail.com> - 2020-03-25 15:05 +0300
            Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-25 10:04 -0400
    Re: Comma operator in for() statements David Brown <david.brown@hesbynett.no> - 2020-03-22 14:49 +0100
  Re: Comma operator in for() statements Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2020-03-22 09:24 -0600
    Re: Comma operator in for() statements Geoff <geoff@invalid.invalid> - 2020-03-22 14:51 -0700
      Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-22 20:13 -0400
        Re: Comma operator in for() statements Geoff <geoff@invalid.invalid> - 2020-03-23 12:16 -0700
          Re: Comma operator in for() statements Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-23 13:16 -0700
          Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-23 17:16 -0400
            Re: Comma operator in for() statements scott@slp53.sl.home (Scott Lurndal) - 2020-03-23 22:40 +0000
  Re: Comma operator in for() statements Guillaume <message@bottle.org> - 2020-03-22 17:31 +0100
    Re: Comma operator in for() statements Geoff <geoff@invalid.invalid> - 2020-03-22 12:28 -0700
      Re: Comma operator in for() statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-22 15:35 -0400
        Re: Comma operator in for() statements Geoff <geoff@invalid.invalid> - 2020-03-22 13:43 -0700
  Re: Comma operator in for() statements Les Cargill <lcargill99@comcast.com> - 2020-03-22 13:50 -0500
    Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-22 19:25 +0000
      Re: Comma operator in for() statements David Brown <david.brown@hesbynett.no> - 2020-03-22 21:52 +0100
        Re: Comma operator in for() statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-22 21:15 +0000
          Re: Comma operator in for() statements David Brown <david.brown@hesbynett.no> - 2020-03-23 09:17 +0100
  Re: Comma operator in for() statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-03-27 08:02 -0700

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