Re: I think references should have been const by default

From	James Kuyper <jameskuyper@alumni.caltech.edu>
Newsgroups	comp.lang.c++
Subject	Re: I think references should have been const by default
Date	2021-10-27 11:38 -0400
Organization	A noiseless patient Spider
Message-ID	<slbrqf$cn3$1@dont-email.me> (permalink)
References	(19 earlier) <sl944f$1qlh$1@gioia.aioe.org> <sl96fa$7q9$1@dont-email.me> <sl96ut$1a96$1@gioia.aioe.org> <sl9a29$438$1@dont-email.me> <slb0pj$s2f$1@gioia.aioe.org>

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On 10/27/21 3:57 AM, RacingRabbit@watershipdown.co.uk wrote:
> On Tue, 26 Oct 2021 12:23:37 -0400
> James Kuyper <jameskuyper@alumni.caltech.edu> wrote:
>> On 10/26/21 11:30 AM, RacingRabbit@watershipdown.co.uk wrote:
>>> You said arrays couldn't be declared as parameters. 
>>
>> No, I said "it's not permitted to declare functions that take arrays as
>> arguments, but it is permitted to declare a function parameter as if it
>> were an array."
> 
> There is no difference. As I said, what the compiler does with it under the
> hood is not the point. The syntax declares an array.

The syntax uses [] rather than *. The semantics are those of a pointer,
not an array.

The semantics are NOT "under the hood" - they restrict what you can do
with the function without violating a constraint. They determine what
result you get when you apply the sizeof() or unary & operators to the
parameter. Most importantly, they determine what happens if you write
expressions such as "parameter[1] = 5".

Getting back to my original statement, declaring a parameter with
pointer semantics using the [] syntax does not allow you to pass an
array as the corresponding argument in the function call. All you can
pass is a pointer to the first element of the array - which is what any
lvalue of array type will be converted into if passed as an argument to
such a function.

Since C uses "pass by value" exclusively, if you were able to pass an
array as an argument, then the corresponding parameter would be a
separate array object with a different address, initialized by copying
from the array argument. Evaluation the expression "parameter[1] = 5"
would only affect the parameter, it would have no effect on the array
argument.
You can get some idea of how C would behave if such declarations were
possible, by declaring a struct type containing an array. Such a struct
could be passed into or returned by a function by value. It's
syntactically different from, but semantically equivalent to, passing
around the array itself by value.

The actual C semantics of such a function call are that the
corresponding parameter is a separate pointer object filled in by
copying the value of the pointer that the lvalue was converted to.
Evaluating the expression "parameter[1] = 5" would set the second
element of the array to 5.

Thread

I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-21 05:23 +0000
  Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-21 08:54 +0200
    Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-21 09:48 +0000
      Re: I think references should have been const by default Paavo Helde <myfirstname@osa.pri.ee> - 2021-10-21 12:55 +0300
      Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-21 12:57 +0200
        Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-21 13:40 +0000
          Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-21 15:04 +0100
            Re: I think references should have been const by default Manfred <noname@add.invalid> - 2021-10-21 16:41 +0200
              Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-21 14:57 +0000
            Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-21 14:51 +0000
            Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-21 12:09 -0400
              Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-21 23:49 +0100
                Re: I think references should have been const by default "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-10-21 16:21 -0700
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-22 16:14 +0100
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-22 12:04 -0700
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-22 20:47 +0100
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-22 13:29 -0700
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-23 11:54 +0200
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-23 11:22 +0100
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-23 12:35 +0200
                Re: I think references should have been const by default Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-10-23 13:23 +0100
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-23 13:57 +0100
                Re: I think references should have been const by default Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-10-23 21:02 +0100
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-23 15:07 -0700
                Re: I think references should have been const by default Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-10-23 21:15 -0700
                Re: I think references should have been const by default Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-10-23 21:12 -0700
              Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-22 11:13 +0200
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-22 19:18 -0400
            Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-22 04:41 +0000
              Re: I think references should have been const by default Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2021-10-23 21:30 +0100
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-25 04:51 +0000
                Re: I think references should have been const by default Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2021-10-26 00:53 +0100
            Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-22 09:46 +0200
              Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-22 15:48 +0100
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-23 12:21 +0200
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-23 12:06 +0100
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-23 18:45 +0200
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-23 18:58 +0100
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-24 12:11 +0200
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-24 23:11 +0100
                Re: I think references should have been const by default Öö Tiib <ootiib@hot.ee> - 2021-10-24 16:18 -0700
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-25 00:58 +0100
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-25 08:21 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-25 09:47 +0000
                Re: I think references should have been const by default Bo Persson <bo@bo-persson.se> - 2021-10-25 12:33 +0200
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-25 14:19 +0000
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-25 10:59 -0400
                Re: I think references should have been const by default Manfred <noname@add.invalid> - 2021-10-25 17:56 +0200
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-25 11:11 -0700
                Re: I think references should have been const by default Manfred <noname@add.invalid> - 2021-10-26 17:15 +0200
                Re: I think references should have been const by default Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-10-29 06:41 -0700
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-25 16:14 +0000
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-25 13:14 -0400
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-26 08:18 +0000
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-26 12:39 +0100
                Re: I think references should have been const by default Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-10-26 14:29 +0100
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-26 15:11 +0100
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-26 09:49 -0700
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-26 18:38 +0100
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-26 11:20 -0700
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-26 20:32 +0100
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-26 22:18 +0200
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-27 04:43 +0000
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-27 08:29 +0200
                Re: I think references should have been const by default Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-10-29 06:32 -0700
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-11-01 06:12 +0000
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-11-01 08:53 +0100
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-11-01 11:26 -0400
                Re: I think references should have been const by default "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-11-02 16:19 +0100
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-11-02 12:54 -0400
                Re: I think references should have been const by default Paavo Helde <myfirstname@osa.pri.ee> - 2021-11-02 23:49 +0200
                Re: I think references should have been const by default "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-11-03 00:38 +0100
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-26 14:36 +0000
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-26 15:55 +0100
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-26 15:26 +0000
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-26 20:35 +0100
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-27 04:44 +0000
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-26 11:27 -0400
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-26 10:31 -0400
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-26 14:42 +0000
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-26 11:22 -0400
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-26 15:30 +0000
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-26 12:23 -0400
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-26 12:51 -0400
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-26 14:34 -0400
                Re: I think references should have been const by default "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-10-26 12:57 -0700
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-27 07:57 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-27 08:47 +0000
                Re: I think references should have been const by default JohnnyCameLater@whatsthetime.net - 2021-10-27 14:29 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-28 05:17 +0000
                Re: I think references should have been const by default JohnnyCameLater@whatsthetime.net - 2021-10-28 09:30 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-29 04:47 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-29 05:11 +0000
                Re: I think references should have been const by default JohnnyCameLater@whatsthetime.net - 2021-10-29 08:40 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-11-01 06:15 +0000
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-27 11:07 +0200
                Re: I think references should have been const by default JohnnyCameLater@whatsthetime.net - 2021-10-27 14:30 +0000
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-27 17:30 +0200
                Re: I think references should have been const by default JohnnyCameLater@whatsthetime.net - 2021-10-27 15:46 +0000
                Re: I think references should have been const by default scott@slp53.sl.home (Scott Lurndal) - 2021-10-27 16:13 +0000
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-27 11:39 -0400
                Re: I think references should have been const by default JohnnyCameLater@whatsthetime.net - 2021-10-27 15:51 +0000
                Re: I think references should have been const by default Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-10-27 17:21 +0100
                Re: I think references should have been const by default JohnnyCameLater@whatsthetime.net - 2021-10-28 09:29 +0000
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-28 11:20 +0100
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-27 12:26 -0400
                Re: I think references should have been const by default Anand Hariharan <mailto.anand.hariharan@gmail.com> - 2021-10-31 09:22 -0700
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-11-01 00:13 -0400
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-28 05:20 +0000
                Re: I think references should have been const by default "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-10-27 23:10 -0700
                Re: I think references should have been const by default JohnnyCameLater@whatsthetime.net - 2021-10-28 09:30 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-29 04:51 +0000
                Re: I think references should have been const by default JohnnyCameLater@whatsthetime.net - 2021-10-29 08:39 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-11-01 06:34 +0000
                Re: I think references should have been const by default Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2021-10-27 17:41 +0100
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-27 19:02 +0200
                Re: I think references should have been const by default Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2021-10-27 18:21 +0100
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-27 11:38 -0400
                Re: I think references should have been const by default JohnnyCameLater@whatsthetime.net - 2021-10-27 15:49 +0000
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-27 12:36 -0400
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-27 04:57 +0000
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-25 18:19 +0100
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-25 10:48 -0700
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-26 08:21 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-26 08:37 +0000
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-26 09:02 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-26 11:14 +0000
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-26 14:35 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-27 05:01 +0000
                Re: I think references should have been const by default Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-10-29 06:34 -0700
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-26 10:43 -0400
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-26 15:21 +0000
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-26 22:32 +0200
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-27 05:04 +0000
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-26 10:42 -0400
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-26 14:48 +0000
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-26 11:52 -0400
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-26 10:22 -0700
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-26 10:27 -0700
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-26 14:06 -0400
                Re: I think references should have been const by default Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-10-29 06:45 -0700
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-29 11:11 -0700
                Re: I think references should have been const by default Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-04-25 07:39 -0700
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-04-25 10:59 -0700
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-26 05:29 +0000
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-26 08:53 +0200
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-26 08:23 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-26 08:40 +0000
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-26 05:18 +0000
                Re: I think references should have been const by default David Brown <david.brown@hesbynett.no> - 2021-10-26 09:07 +0200
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-26 11:03 -0400
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-25 10:39 -0400
                Re: I think references should have been const by default Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-25 10:56 -0700
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-25 10:30 -0400
                Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-25 14:39 +0000
                Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-25 11:05 -0400
                Re: I think references should have been const by default "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-10-25 12:45 -0700
                Re: I think references should have been const by default "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-10-26 11:20 -0700
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-25 05:00 +0000
                Re: I think references should have been const by default Bart <bc@freeuk.com> - 2021-10-25 12:13 +0100
                Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-26 05:36 +0000
                Re: I think references should have been const by default Manfred <noname@add.invalid> - 2021-10-25 16:58 +0200
    Re: I think references should have been const by default "daniel...@gmail.com" <danielaparker@gmail.com> - 2021-10-22 12:28 -0700
  Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-21 09:12 +0000
    Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-21 09:52 +0000
      Re: I think references should have been const by default RacingRabbit@watershipdown.co.uk - 2021-10-21 10:36 +0000
        Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-22 04:45 +0000
    Re: I think references should have been const by default James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-10-21 12:07 -0400
  Re: I think references should have been const by default Paavo Helde <myfirstname@osa.pri.ee> - 2021-10-21 12:18 +0300
  Re: I think references should have been const by default Bonita Montero <Bonita.Montero@gmail.com> - 2021-10-21 13:13 +0200
    Re: I think references should have been const by default Bo Persson <bo@bo-persson.se> - 2021-10-21 15:08 +0200
    Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-22 04:45 +0000
      Re: I think references should have been const by default Bonita Montero <Bonita.Montero@gmail.com> - 2021-10-22 07:55 +0200
        Re: I think references should have been const by default Branimir Maksimovic <branimir.maksimovic@icloud.com> - 2021-10-22 11:21 +0000
  Re: I think references should have been const by default "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-10-21 13:22 +0200
    Re: I think references should have been const by default Juha Nieminen <nospam@thanks.invalid> - 2021-10-22 04:48 +0000
  Re: I think references should have been const by default Manfred <noname@add.invalid> - 2021-10-21 13:57 +0200
  Re: I think references should have been const by default Branimir Maksimovic <branimir.maksimovic@icloud.com> - 2021-10-21 21:27 +0000
  Re: I think references should have been const by default Jorgen Grahn <grahn+nntp@snipabacken.se> - 2021-10-24 14:20 +0000

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