setlocale - set the current locale
char *setlocale(int category, const char *locale);
() function is used to set or query the program's current
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.
||All of the locale
||Formatting of addresses and geography-related items (*)
||Metadata describing the locale (*)
||Settings related to measurements (metric versus US customary) (*)
||Localizable natural-language messages
||Formatting of monetary values
||Formatting of salutations for persons (*)
||Formatting of nonmonetary numeric values
||Settings related to the standard paper size (*)
||Formats to be used with telephone services (*)
||Formatting of date and time values
The categories marked with an asterisk in the above table are GNU extensions.
For further information on these locale categories, see locale
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
is an empty string, ""
, 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
), the environment variable LC_ALL
is inspected, next
the environment variable with the same name as the category (see the table
above), 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"
is a portable
locale; it exists on all conforming systems.
A locale name is typically of the form
is an ISO 639 language code, territory
is an ISO 3166
country code, and codeset
is a character set or encoding identifier
. For a list of all supported locales,
try "locale -a" (see locale
is NULL, the current locale is only queried, not modified.
On startup of the main program, the portable "C"
selected as default. A program may be made portable to all locales by calling:
after program initialization, by using the values returned from a
(3) call for locale-dependent information, by using the
multibyte and wide character functions for text processing if MB_CUR_MAX
, and by using strcoll
(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.
For an explanation of the terms used in this section, see attributes
||MT-Unsafe const:locale env
POSIX.1-2001, POSIX.1-2008, C89, C99.
The C standards specify only the categories LC_ALL
, and LC_TIME
POSIX.1 adds LC_MESSAGES
. The remaining categories are GNU extensions.