Re: getline() problem

From	Andrey Tarasevich <andreytarasevich@hotmail.com>
Newsgroups	comp.lang.c++
Subject	Re: getline() problem
Date	2022-04-25 11:03 -0700
Organization	A noiseless patient Spider
Message-ID	<t46np1$5uj$1@dont-email.me> (permalink)
References	(3 earlier) <t41er4$35r34$1@portraits.wsisiz.edu.pl> <t41hkn$6p9$1@dont-email.me> <t45de2$1sln$2@gioia.aioe.org> <t46f86$or8$1@dont-email.me> <Kwz9K.23424$x9Ea.11744@fx45.iad>

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On 4/25/2022 8:56 AM, Scott Lurndal wrote:
>>
>> As a general rule, you should not write data to a text stream if it
>> contains any feature invalidating that guarantee, and you should not
>> read data from a text stream if it contains any of those things.
> 
> As a general rule, your general rule only applies to Windows.  On Unix
> and Unix-like systems, there is no functional difference between text
> and binary.

That's catastrophically incorrect on more than one level.

This is the same fallacy that is often used by numerous "UB deniers", 
claiming that on their hardware/OS platform some forms of "undefined 
behavior" are supposedly "perfectly defined" because they know how their 
platform/hardware/OS will react in some specific situation.

They just can't grasp this little bit of understanding that the primary 
source of "undefined" in undefined behavior in _not_ their hardware/OS. 
It is the abstract language semantics implemented by the compiler. The 
compiler that actively uses UB as an optimization opportunity at a 
rather abstract level. It doesn't even get to the hardware/OS level. 
Hardware/OS matter very little.

The same reasoning can be applied to the matter of binary vs. text streams.

For example, the very moment the abstract specification of text stream 
will provide optimization opportunities (or any other benefits) to the 
implementation of C or C++ standard library, this implementation 
might/will take advantage of these opportunities to make text streams 
work more efficiently than binary streams (within the spec, of course). 
It will break text vs. binary compatibility and it will do this with 
complete disregard to the fact that the underlying OS makes no 
difference between text and binary.

I'm exaggerating, of course, because it something like this ever happens 
to Unix-like I/O, the raging uproar the affected parties will be 
deafening. (We've heard it before with strict aliasing, strict overflow, 
`memcpy` that copies backwards etc.) Nobody will dare to break 
binary-text equivalence of Unix-like systems (and POSIX won't allow 
this). But in essence... this is just a wall of entrenched incompetence 
too high to climb over.

-- 
Best regards,
Andrey Tarasevich

Thread

getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-23 19:07 +0200
  Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-23 10:17 -0700
    Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-23 19:40 +0200
      Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-23 19:59 +0200
        Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-23 21:47 +0300
          Re: getline() problem Juha Nieminen <nospam@thanks.invalid> - 2022-04-25 06:00 +0000
            Re: getline() problem Öö Tiib <ootiib@hot.ee> - 2022-04-25 00:12 -0700
            Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-25 11:40 +0300
            Re: getline() problem James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-04-25 11:37 -0400
              Re: getline() problem Vir Campestris <vir.campestris@invalid.invalid> - 2022-04-25 16:54 +0100
                Re: getline() problem James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-04-25 12:29 -0400
                Re: getline() problem scott@slp53.sl.home (Scott Lurndal) - 2022-04-25 17:29 +0000
                Re: getline() problem Manfred <noname@add.invalid> - 2022-04-25 20:17 +0200
                Re: getline() problem Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-04-25 10:19 -0700
                Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 10:41 -0700
                Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-25 21:58 +0300
              Re: getline() problem scott@slp53.sl.home (Scott Lurndal) - 2022-04-25 15:56 +0000
                Re: getline() problem James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-04-25 13:12 -0400
                Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 11:03 -0700
                Re: getline() problem scott@slp53.sl.home (Scott Lurndal) - 2022-04-25 19:05 +0000
                Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 12:48 -0700
                Re: getline() problem Ben <ben.usenet@bsb.me.uk> - 2022-04-25 21:46 +0100
                Re: getline() problem Juha Nieminen <nospam@thanks.invalid> - 2022-04-26 05:43 +0000
                Re: getline() problem David Brown <david.brown@hesbynett.no> - 2022-04-26 09:36 +0200
                Re: getline() problem Juha Nieminen <nospam@thanks.invalid> - 2022-04-26 09:18 +0000
                Re: getline() problem Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-04-26 02:47 -0700
                Re: getline() problem Juha Nieminen <nospam@thanks.invalid> - 2022-04-26 11:06 +0000
                Re: getline() problem David Brown <david.brown@hesbynett.no> - 2022-04-26 15:52 +0200
                Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-26 07:04 -0700
                Re: getline() problem Manfred <noname@add.invalid> - 2022-04-26 16:49 +0200
                Re: getline() problem James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-04-26 12:01 -0400
                Re: getline() problem James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-04-26 11:49 -0400
                Re: getline() problem Manfred <noname@add.invalid> - 2022-04-25 20:23 +0200
            Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 10:33 -0700
              Re: getline() problem "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2022-04-25 10:52 -0700
                Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 11:08 -0700
                Re: getline() problem "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2022-04-25 21:18 -0700
                Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 22:04 -0700
              Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-25 22:06 +0300
                Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 13:02 -0700
        Re: getline() problem Barry Schwarz <schwarzb@delq.com> - 2022-04-23 12:54 -0700
        Re: getline() problem Montmorency <none@none.com> - 2022-04-23 14:45 -0700
          Re: getline() problem Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-04-23 16:49 -0700
            Re: getline() problem Ben <ben.usenet@bsb.me.uk> - 2022-04-24 01:04 +0100
              Re: getline() problem Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-04-23 18:24 -0700
                Re: getline() problem Ben <ben.usenet@bsb.me.uk> - 2022-04-24 03:16 +0100
                Re: getline() problem Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-04-24 22:51 -0700
                Re: getline() problem Ben <ben.usenet@bsb.me.uk> - 2022-04-25 11:07 +0100
            Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-23 17:15 -0700
              Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-23 18:23 -0700
          Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-24 05:28 +0200
  Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-25 12:41 +0200
    Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-25 14:33 +0300
    Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-25 18:53 +0200
      Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-25 22:08 +0300
        Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-26 09:01 +0200
          Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-26 11:15 +0300

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