setlocale — set the current locale
#include <locale.h>
char
*setlocale( |
int | category, |
const char * | locale) ; |
The setlocale
() function is
used to set or query the program's current locale.
If locale
is not
NULL, the program's current locale is modified according to
the arguments. The argument category
determines which parts
of the program's current locale should be modified.
LC_ALL
for all of the locale.
LC_COLLATE
for regular expression matching (it determines the meaning of range expressions and equivalence classes) and string collation.
LC_CTYPE
for regular expression matching, character classification, conversion, case-sensitive comparison, and wide character functions.
LC_MESSAGES
for localizable natural-language messages.
LC_MONETARY
for monetary formatting.
LC_NUMERIC
for number formatting (such as the decimal point and the thousands separator).
LC_TIME
for time and date formatting.
The argument locale
is a pointer to a
character string containing the required setting of
category
. Such a
string is either a well-known constant like "C" or "da_DK"
(see below), or an opaque string that was returned by another
call of setlocale
().
If locale
is
""
, each part of
the locale that should be modified is set according to the
environment variables. The details are implementation
dependent. For glibc, first (regardless of category
), the environment
variable LC_ALL is inspected, next the environment variable
with the same name as the category (LC_COLLATE, LC_CTYPE,
LC_MESSAGES, LC_MONETARY, LC_NUMERIC, LC_TIME) and finally
the environment variable LANG. The first existing environment
variable is used. If its value is not a valid locale
specification, the locale is unchanged, and setlocale
() returns NULL.
The locale "C"
or "POSIX"
is a
portable locale; its LC_CTYPE part corresponds to the 7-bit
ASCII character set.
A locale name is typically of the form language
[_territory
][.codeset
][@modifier
], where language
is an ISO 639
language code, territory
is an ISO 3166
country code, and codeset
is a character set or
encoding identifier like ISO-8859-1
or UTF-8
. For a list of all
supported locales, try "locale −a", cf. locale(1).
If locale
is NULL,
the current locale is only queried, not modified.
On startup of the main program, the portable "C"
locale is selected as
default. A program may be made portable to all locales by
calling setlocale(LC_ALL, ""
) after program initialization, by using the
values returned from a localeconv(3) call for
locale-dependent information, by using the multi-byte and
wide character functions for text processing if MB_CUR_MAX > 1, and by using
strcoll(3), wcscoll(3) or strxfrm(3), wcsxfrm(3) to compare
strings.
A successful call to setlocale
() returns an opaque string that
corresponds to the locale set. This string may be allocated
in static storage. The string returned is such that a
subsequent call with that string and its associated category
will restore that part of the process's locale. The return
value is NULL if the request cannot be honored.
Linux (that is, GNU libc) supports the portable locales
"C"
and "POSIX"
. In the good old days
there used to be support for the European Latin-1 "ISO-8859-1"
locale (e.g. in
libc-4.5.21 and libc-4.6.27), and the Russian "KOI-8"
(more precisely,
"koi-8r") locale (e.g. in libc-4.6.27), so that having an
environment variable LC_CTYPE=ISO-8859-1 sufficed to make
isprint(3) return the right
answer. These days non-English speaking Europeans have to
work a bit harder, and must install actual locale files.
locale(1), localedef(1), isalpha(3), localeconv(3), nl_langinfo(3), rpmatch(3), strcoll(3), strftime(3), charsets(4), locale(7)
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