NAME

       setlocale - set the current locale

LIBRARY

       Standard C library (libc, -lc)

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.

       Category            Governs
       LC_ALL              All of the locale
       LC_ADDRESS          Formatting of addresses and geography-related items (*)
       LC_COLLATE          String collation
       LC_CTYPE            Character classification
       LC_IDENTIFICATION   Metadata describing the locale (*)
       LC_MEASUREMENT      Settings related to measurements (metric versus US customary) (*)
       LC_MESSAGES         Localizable natural-language messages
       LC_MONETARY         Formatting of monetary values
       LC_NAME             Formatting of salutations for persons (*)
       LC_NUMERIC          Formatting of nonmonetary numeric values
       LC_PAPER            Settings related to the standard paper size (*)
       LC_TELEPHONE        Formats to be used with telephone services (*)
       LC_TIME             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(7).

       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 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 category), 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" or "POSIX" is a portable locale; it exists on all conforming systems.

       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" (see 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, and then:

       •  using the values returned from a localeconv(3) call for locale-dependent information;

       •  using the multibyte and wide character functions for text processing if MB_CUR_MAX > 1;

       •  using strcoll(3) and strxfrm(3) to compare strings; and

       •  using wcscoll(3) and wcsxfrm(3) to compare wide-character 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.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌────────────────────────────────────────────┬───────────────┬────────────────────────────┐
       │Interface                                   │ Attribute     │ Value                      │
       ├────────────────────────────────────────────┼───────────────┼────────────────────────────┤
       │setlocale()                                 │ Thread safety │ MT-Unsafe const:locale env │
       └────────────────────────────────────────────┴───────────────┴────────────────────────────┘

STANDARDS

       POSIX.1-2001, POSIX.1-2008, C99.

       The  C  standards  specify  only the categories LC_ALL, LC_COLLATE, LC_CTYPE, LC_MONETARY,
       LC_NUMERIC, and LC_TIME.  POSIX.1 adds LC_MESSAGES.   The  remaining  categories  are  GNU
       extensions.

SEE ALSO

       locale(1),    localedef(1),   isalpha(3),   localeconv(3),   nl_langinfo(3),   rpmatch(3),
       strcoll(3), strftime(3), charsets(7), locale(7)