Re: C++ comma operator ?

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From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.lang.c++
Subject	Re: C++ comma operator ?
Date	Mon, 03 Oct 2022 02:38:57 -0700
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Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:

> Lynn McGuire <lynnmcguire5@gmail.com> writes:
>
>> Is this C++ statement using the comma operator ?
>>
>>       write(6, "(3(1x,i3),1x,f12.6,1x,f12.6)"),
>>        hkl(1, i), hkl(2, i), hkl(3, i), f_calc(1, i), f_calc(2, i);
>
> Yes, five of them, easily seen by reformatting the code:
>
>     write(6, "(3(1x,i3),1x,f12.6,1x,f12.6)"),
>     hkl(1, i),
>     hkl(2, i),
>     hkl(3, i),
>     f_calc(1, i),
>     f_calc(2, i);
>
> Assuming there's no macro funny business going on, that's 6
> function calls (or macro invocations?) separated by comma
> operators.  (The commas separating function arguments are of
> course not comma operators.)
>
> Replacing the comma at the end of each line by a semicolon (and
> possibly surrounding the whole thing with curly braces) yields
> equivalent code.

In C++ that rule does not hold, because of the possibility of an
overloaded operator,().  Indeed in this case it appears that
there is an operator,() overload, and that is what makes this
statement work;  changing the statement to be a series of
semicolon-terminated statements wouldn't work at all.

Thread

C++ comma operator ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-09-29 23:48 -0500
  Re: C++ comma operator ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-09-30 00:01 -0500
    Re: C++ comma operator ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-09-30 00:03 -0500
  Re: C++ comma operator ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-09-30 01:05 -0400
    Re: C++ comma operator ? red floyd <no.spam.here@its.invalid> - 2022-09-29 22:45 -0700
      Re: C++ comma operator ? scott@slp53.sl.home (Scott Lurndal) - 2022-09-30 15:16 +0000
        Re: C++ comma operator ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-09-30 13:53 -0500
          Re: C++ comma operator ? Gawr Gura <gawrgura@mail.hololive.com> - 2022-09-30 13:17 -0700
          Re: C++ comma operator ? scott@slp53.sl.home (Scott Lurndal) - 2022-10-01 16:56 +0000
            Re: C++ comma operator ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-01 13:13 -0500
            Re: C++ comma operator ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-10-03 02:32 -0700
              Re: C++ comma operator ? Juha Nieminen <nospam@thanks.invalid> - 2022-10-03 10:48 +0000
    Re: C++ comma operator ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-09-30 13:32 -0500
      Re: C++ comma operator ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-01 14:30 -0500
        Re: C++ comma operator ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-10-02 16:08 -0400
    Re: C++ comma operator ? Manfred <noname@add.invalid> - 2022-10-01 01:03 +0200
      Re: C++ comma operator ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-09-30 23:09 -0500
  Re: C++ comma operator ? Gawr Gura <gawrgura@mail.hololive.com> - 2022-09-29 23:19 -0700
    Re: C++ comma operator ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-09-30 13:31 -0500
  Re: C++ comma operator ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-30 12:41 -0700
    Re: C++ comma operator ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-10-03 02:38 -0700
  Re: C++ comma operator ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-09-30 23:48 -0500

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