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SETLOCALE(3)               Linux Programmer's Manual              SETLOCALE(3)
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 accord-
       ing  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 cate-
       gory), the environment variable LC_ALL is inspected, next the  environ-
       ment variable with the same name as the category (see the table above),
       and finally the environment variable LANG.  The first existing environ-
       ment  variable  is used.  If its value is not a valid locale specifica-
       tion, the locale is unchanged, and setlocale() returns NULL.
       The locale "C" or "POSIX" is a portable locale; it exists on  all  con-
       forming systems.
       A  locale  name  is  typically  of the form language[_territory][.code-
       set][@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, 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  corre-
       sponds to the locale set.  This string may be allocated in static stor-
       age.  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 |
       +------------+---------------+----------------------------+
CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, C89, 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_MES-
       SAGES.  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)
COLOPHON
       This  page  is  part of release 4.15 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       https://www.kernel.org/doc/man-pages/.
GNU                               2017-09-15                      SETLOCALE(3)