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NAME
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 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 multibyte 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.
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
C89, C99, POSIX.1-2001.
NOTES
Linux (that is, glibc) 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.
SEE ALSO
locale(1), localedef(1), isalpha(3), localeconv(3), nl_langinfo(3), rpmatch(3), strcoll(3), strftime(3), charsets(7), locale(7)
COLOPHON
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