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Re: Is wchar_t really useful?

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On 13.11.2015 19:55, James Kuyper wrote:
> On 11/13/2015 12:24 PM, Philipp Klaus Krause wrote:
>> Could an implementation decide that characters in the execution
>> character set are just the values of char? wchar_t could be 8 bits.
>> […]
>> Would this violate "In a character constant or string literal, members
>> of the execution character set shall be represented by corresponding
>> members of the source character set […]" from 5.2.1?
>> Unfortunately, that would mean that functions like mbrtoc32() couldn't
>> convert to UTF-32 anymore, since they are supposed to read and interpret
>> only one multibyte character at a time.
> 
> How did you reach that conclusion? mbrtoc32() reads multiple characters
> through it's char* parameter:
> 
> "If s is not a null pointer, the mbrtoc32 function inspects at most n
> bytes beginning with the byte pointed to by s to determine the number of
> bytes needed to complete the next multibyte character (including any
> shift sequences)."

"If the function determines that the next multibyte character is
complete and valid, it determines the values of the corresponding wide
characters and then, if pc32 is not a null pointer, stores the value of
the first (or only) such character in the object pointed to by pc32."

So if the implementation considers all bytes in utf-8 sequences to be
individual characters, then mbrtoc32() will have to write out at least
one char32_t for each char it reads.
Such an implementation doesn't look that absurd to me: After all in the
end mutiple uncidoe code points will have to be converted to one glyph
anyway, due to combining characters. So even with UTF-32 we do not have
a 1-to-1 correspondance of characters and glyphs.

Philipp

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Thread

Is wchar_t really useful? Philipp Klaus Krause <pkk@spth.de> - 2015-11-09 12:02 +0100
  Re: Is wchar_t really useful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-09 03:24 -0800
    Re: Is wchar_t really useful? Stephen Sprunk <stephen@sprunk.org> - 2015-11-10 18:33 -0600
      Re: Is wchar_t really useful? Ian Collins <ian-news@hotmail.com> - 2015-11-11 13:56 +1300
  Re: Is wchar_t really useful? James Kuyper <jameskuyper@verizon.net> - 2015-11-09 09:03 -0500
    Re: Is wchar_t really useful? Philipp Klaus Krause <pkk@spth.de> - 2015-11-12 15:22 +0100
      Re: Is wchar_t really useful? James Kuyper <jameskuyper@verizon.net> - 2015-11-12 10:04 -0500
        Re: Is wchar_t really useful? Philipp Klaus Krause <pkk@spth.de> - 2015-11-12 16:44 +0100
          Re: Is wchar_t really useful? James Kuyper <jameskuyper@verizon.net> - 2015-11-12 11:29 -0500
            Re: Is wchar_t really useful? supercat@casperkitty.com - 2015-11-12 09:14 -0800
              Re: Is wchar_t really useful? Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-14 11:50 -0800
                Re: Is wchar_t really useful? supercat@casperkitty.com - 2015-11-15 13:44 -0800
                Re: Is wchar_t really useful? Philipp Klaus Krause <pkk@spth.de> - 2015-11-15 22:50 +0100
                Re: Is wchar_t really useful? supercat@casperkitty.com - 2015-11-15 14:46 -0800
                Re: Is wchar_t really useful? raltbos@xs4all.nl (Richard Bos) - 2015-11-17 22:34 +0000
                Re: Is wchar_t really useful? Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-16 07:25 -0800
            Re: Is wchar_t really useful? Philipp Klaus Krause <pkk@spth.de> - 2015-11-13 17:26 +0100
              Re: Is wchar_t really useful? James Kuyper <jameskuyper@verizon.net> - 2015-11-13 13:36 -0500
                Re: Is wchar_t really useful? Stephen Sprunk <stephen@sprunk.org> - 2015-11-13 16:37 -0600
                Re: Is wchar_t really useful? James Kuyper <jameskuyper@verizon.net> - 2015-11-13 17:58 -0500
              Re: Is wchar_t really useful? Stephen Sprunk <stephen@sprunk.org> - 2015-11-13 16:01 -0600
                Re: Is wchar_t really useful? Philipp Klaus Krause <pkk@spth.de> - 2015-11-13 23:36 +0100
    Re: Is wchar_t really useful? Philipp Klaus Krause <pkk@spth.de> - 2015-11-12 15:28 +0100
      Re: Is wchar_t really useful? James Kuyper <jameskuyper@verizon.net> - 2015-11-12 10:26 -0500
    Re: Is wchar_t really useful? Stephen Sprunk <stephen@sprunk.org> - 2015-11-12 14:27 -0600
  Re: Is wchar_t really useful? Lőrinczy Zsigmond <nospam@for.me> - 2015-11-13 05:02 +0100
    Re: Is wchar_t really useful? Philipp Klaus Krause <pkk@spth.de> - 2015-11-13 11:52 +0100
      Re: Is wchar_t really useful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-13 05:17 -0800
        Re: Is wchar_t really useful? Stephen Sprunk <stephen@sprunk.org> - 2015-11-13 12:58 -0600
        Re: Is wchar_t really useful? supercat@casperkitty.com - 2015-11-13 11:14 -0800
    Re: Is wchar_t really useful? Stephen Sprunk <stephen@sprunk.org> - 2015-11-13 12:45 -0600
  Re: Is wchar_t really useful? Philipp Klaus Krause <pkk@spth.de> - 2015-11-13 18:24 +0100
    Re: Is wchar_t really useful? James Kuyper <jameskuyper@verizon.net> - 2015-11-13 13:55 -0500
      Re: Is wchar_t really useful? Philipp Klaus Krause <pkk@spth.de> - 2015-11-13 20:39 +0100
        Re: Is wchar_t really useful? James Kuyper <jameskuyper@verizon.net> - 2015-11-13 14:54 -0500
        Re: Is wchar_t really useful? Stephen Sprunk <stephen@sprunk.org> - 2015-11-13 17:04 -0600

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