setlocale - set the current locale.
SYNOPSIS
#include <locale.h>
char *setlocale(int category, const char * locale);
DESCRIPTION
The setlocale() function is used to set or query the pro
gram's current locale.
If locale is not NULL, the program's current locale is
modified according to the arguments. The argument cate
gory 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 classi
fication, 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,
the environment variable LANG. The first existing envi
ronment variable is used. If its value is not a valid
locale specification, the locale is unchanged, and setlo
cale 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[_terri
tory][.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 pro
gram initialization, by using the values returned from a
localeconv() 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(),
wcscoll() or strxfrm(), wcsxfrm() to compare strings.
RETURN VALUE
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.
CONFORMING TO
ANSI C, POSIX.1
NOTES
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() return the right answer. These
days non-English speaking Europeans have to work a bit
harder, and must install actual locale files.
SEE ALSO
locale(1), localedef(1), strcoll(3), isalpha(3), locale
conv(3), strftime(3), charsets(4), locale(7)
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