Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #164674

Re: UTF-8 strings in C

Show all headers | View raw

On 1/27/22 06:33, Otto J. Makela wrote:
> ram@zedat.fu-berlin.de (Stefan Ram) wrote:
>
>> Here:
>
> The end result is exactly the same as with my program,
> mblen() returns -1.
>
> James Kuyper <jameskuyper@alumni.caltech.edu> understood it, I need to
> ask for the default locale. I'm a bit stumped as to why so.

Note: while I referred to it as the "default" locale, that's a bad term
for it, since the "C" locale is the true default:

"At program startup, the equivalent of
setlocale(LC_ALL, "C");
is executed." (7.11.1.1p4)

"... a value of "" for locale specifies the locale-specific native
environment." (7.11.1.1p3), so it would be better to call it the
"native" locale.

"In the "C" locale, isalpha returns true only for the characters for
which isupper or islower is true." (7.4.1.2p2)

"In the "C" locale, islower returns true only for the lowercase letters
(as defined in 5.2.1)." (7.4.1.7p2)

"In the "C" locale, isupper returns true only for the uppercase letters
(as defined in 5.2.1)." (7.4.1.11p2)

"... the 26 _uppercase letters_ of the Latin alphabet
A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z

the 26 _lowercase letters_ of the Latin alphabet
a b c d e f g h i j k l m
n o p q r s t u v w x y z" (5.2.1p2)

Note that the phrases "uppercase letters" and "lowercase letters" are in
italics, an ISO convention indicating that the clause in which they
appear constitutes the official definition for those terms within this
document.

Thus, isalpha() can only be true in the "C" locale for the 26 letters of
the latin alphabet. That's not quite the same as requiring that those be
the only valid character encodings. Note, in particular, that it's not
possible to pass a member of the extended character set to isalpha() if
that member's encoding takes more than 1 byte, so nothing the standard
says about isalpha() can constrain how such characters are treated. Such
a character could be converted to wchar_t and passed to iswalpha(), but
that function has no special specifications for the "C" locale. However,
those facts certainly don't encourage support for additional valid
character encodings in the "C" locale.

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: UTF-8 strings in C Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-10 07:17 +0100
  Re: UTF-8 strings in C Mateusz Viste <mateusz@xyz.invalid> - 2022-01-10 09:32 +0100
    Re: UTF-8 strings in C Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-10 11:26 +0100
      Re: UTF-8 strings in C Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-10 11:55 +0100
        Re: UTF-8 strings in C Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-10 14:38 +0100
          Re: UTF-8 strings in C om@iki.fi (Otto J. Makela) - 2022-01-14 14:26 +0200
            Re: UTF-8 strings in C om@iki.fi (Otto J. Makela) - 2022-01-14 16:07 +0200
              Re: UTF-8 strings in C Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-14 15:42 +0100
              Re: UTF-8 strings in C Philipp Klaus Krause <pkk@spth.de> - 2022-01-15 09:08 +0100
                Re: UTF-8 strings in C om@iki.fi (Otto J. Makela) - 2022-01-22 11:44 +0200
                Re: UTF-8 strings in C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-22 04:48 -0800
                Re: UTF-8 strings in C Richard Damon <Richard@Damon-Family.org> - 2022-01-22 08:27 -0500
                Re: UTF-8 strings in C James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-01-22 14:25 -0500
                Re: UTF-8 strings in C om@iki.fi (Otto J. Makela) - 2022-01-27 13:32 +0200
                Re: UTF-8 strings in C om@iki.fi (Otto J. Makela) - 2022-01-27 13:33 +0200
                Re: UTF-8 strings in C James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-01-27 11:08 -0500
                Re: UTF-8 strings in C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-03 22:23 -0800
          Re: UTF-8 strings in C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-14 04:41 -0800
            Re: UTF-8 strings in C Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-14 14:43 +0100
              Re: UTF-8 strings in C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-14 05:45 -0800
                Re: UTF-8 strings in C Mateusz Viste <mateusz@xyz.invalid> - 2022-01-14 15:10 +0100
                Re: UTF-8 strings in C Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-14 15:43 +0100
                Re: UTF-8 strings in C Bart <bc@freeuk.com> - 2022-01-14 15:50 +0000
                Re: UTF-8 strings in C Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-14 17:50 +0100
                Re: UTF-8 strings in C Mateusz Viste <mateusz@xyz.invalid> - 2022-01-14 17:17 +0100
                Re: UTF-8 strings in C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-01-14 08:34 -0800
                Re: UTF-8 strings in C Mateusz Viste <mateusz@xyz.invalid> - 2022-01-14 17:42 +0100
                Re: UTF-8 strings in C Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-14 17:51 +0100
                Re: UTF-8 strings in C Mateusz Viste <mateusz@xyz.invalid> - 2022-01-14 18:07 +0100
                Re: UTF-8 strings in C Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-14 18:19 +0100
                Re: UTF-8 strings in C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-07 09:02 -0800

csiph-web