LOCALE(7)                  Linux Programmer's Manual                 LOCALE(7)
NAME
       locale - description of multilanguage support

SYNOPSIS
       #include <locale.h>

DESCRIPTION
       A  locale is a set of language and cultural rules.  These cover aspects
       such as language for messages, different character sets,  lexicographic
       conventions,  and  so  on.  A program needs to be able to determine its
       locale and act accordingly to be portable to different cultures.

       The header <locale.h> declares data types, functions and  macros  which
       are useful in this task.

       The  functions  it declares are setlocale(3) to set the current locale,
       and localeconv(3) to get information about number formatting.

       There are different categories for locale information a  program  might
       need; they are declared as macros.  Using them as the first argument to
       the setlocale(3) function, it is possible to set one of  these  to  the
       desired locale:

       LC_ADDRESS (GNU extension, since glibc 2.2)
              Change   settings   that  describe  the  formats  (e.g.,  postal
              addresses) used  to  describe  locations  and  geography-related
              items.  Applications that need this information can use nl_lang-
              info(3)   to   retrieve   nonstandard    elements,    such    as
              _NL_ADDRESS_COUNTRY_NAME  (country  name, in the language of the
              locale) and _NL_ADDRESS_LANG_NAME (language name,  in  the  lan-
              guage of the locale), which return strings such as "Deutschland"
              and "Deutsch" (for  German-language  locales).   (Other  element
              names are listed in <langinfo.h>.)

       LC_COLLATE
              This  category  governs the collation rules used for sorting and
              regular expressions, including character equivalence classes and
              multicharacter collating elements.  This locale category changes
              the behavior of the functions strcoll(3) and  strxfrm(3),  which
              are used to compare strings in the local alphabet.  For example,
              the German sharp s is sorted as "ss".

       LC_CTYPE
              This category determines the interpretation of byte sequences as
              characters (e.g., single versus multibyte characters), character
              classifications (e.g., alphabetic or digit), and the behavior of
              character  classes.  On glibc systems, this category also deter-
              mines the  character  transliteration  rules  for  iconv(1)  and
              iconv(3).  It changes the behavior of the character handling and
              classification functions, such as isupper(3) and toupper(3), and
              the multibyte character functions such as mblen(3) or wctomb(3).

       LC_IDENTIFICATION (GNU extension, since glibc 2.2)
              Change  settings  that  relate  to  the metadata for the locale.
              Applications that need this information can  use  nl_langinfo(3)
              to   retrieve  nonstandard  elements,  such  as  _NL_IDENTIFICA-
              TION_TITLE (title of this locale document)  and  _NL_IDENTIFICA-
              TION_TERRITORY (geographical territory to which this locale doc-
              ument applies), which might  return  strings  such  as  "English
              locale  for the USA" and "USA".  (Other element names are listed
              in <langinfo.h>.)

       LC_MONETARY
              This category  determines  the  formatting  used  for  monetary-
              related  numeric  values.  This changes the information returned
              by localeconv(3), which describes the way  numbers  are  usually
              printed,  with  details  such  as  decimal  point versus decimal
              comma.  This information is  internally  used  by  the  function
              strfmon(3).

       LC_MESSAGES
              This  category  affects  the language in which messages are dis-
              played and what an affirmative or negative  answer  looks  like.
              The  GNU  C  library  contains  the gettext(3), ngettext(3), and
              rpmatch(3) functions to ease the use of this  information.   The
              GNU  gettext family of functions also obey the environment vari-
              able LANGUAGE (containing a colon-separated list of locales)  if
              the category is set to a valid locale other than "C".  This cat-
              egory also affects the behavior of catopen(3).

       LC_MEASUREMENT (GNU extension, since glibc 2.2)
              Change the settings relating to the measurement  system  in  the
              locale  (i.e.,  metric versus US customary units).  Applications
              can use nl_langinfo(3) to retrieve the nonstandard  _NL_MEASURE-
              MENT_MEASUREMENT element, which returns a pointer to a character
              that has the value 1 (metric) or 2 (US customary units).

       LC_NAME (GNU extension, since glibc 2.2)
              Change settings that describe the formats used to  address  per-
              sons.   Applications that need this information can use nl_lang-
              info(3)   to   retrieve   nonstandard    elements,    such    as
              _NL_NAME_NAME_MR    (general    salutation    for    men)    and
              _NL_NAME_NAME_MS (general salutation for women) elements,  which
              return  strings  such  as "Herr" and "Frau" (for German-language
              locales).  (Other element names are listed in <langinfo.h>.)

       LC_NUMERIC
              This category determines the formatting rules used for  nonmone-
              tary  numeric  values--for  example, the thousands separator and
              the radix character (a period  in  most  English-speaking  coun-
              tries, but a comma in many other regions).  It affects functions
              such as printf(3), scanf(3), and  strtod(3).   This  information
              can also be read with the localeconv(3) function.

       LC_PAPER (GNU extension, since glibc 2.2)
              Change  the  settings relating to the dimensions of the standard
              paper size (e.g., US letter versus A4).  Applications that  need
              the  dimensions  can  obtain  them  by  using  nl_langinfo(3) to
              retrieve the nonstandard  _NL_PAPER_WIDTH  and  _NL_PAPER_HEIGHT
              elements,  which  return int values specifying the dimensions in
              millimeters.

       LC_TELEPHONE (GNU extension, since glibc 2.2)
              Change settings that describe the formats to be used with  tele-
              phone services.  Applications that need this information can use
              nl_langinfo(3)  to  retrieve  nonstandard  elements,   such   as
              _NL_TELEPHONE_INT_PREFIX (international prefix used to call num-
              bers in this locale), which returns a string such as  "49"  (for
              Germany).  (Other element names are listed in <langinfo.h>.)

       LC_TIME
              This category governs the formatting used for date and time val-
              ues.  For example, most of Europe uses a  24-hour  clock  versus
              the  12-hour  clock  used  in the United States.  The setting of
              this category affects the behavior of functions  such  as  strf-
              time(3) and strptime(3).

       LC_ALL All of the above.

       If  the second argument to setlocale(3) is an empty string, "", for the
       default locale, it is determined using the following steps:

       1.     If there is a non-null environment variable LC_ALL, the value of
              LC_ALL is used.

       2.     If an environment variable with the same name as one of the cat-
              egories above exists and is non-null, its value is used for that
              category.

       3.     If  there  is a non-null environment variable LANG, the value of
              LANG is used.

       Values about local numeric formatting is made  available  in  a  struct
       lconv  returned  by the localeconv(3) function, which has the following
       declaration:

         struct lconv {

             /* Numeric (nonmonetary) information */

             char *decimal_point;     /* Radix character */
             char *thousands_sep;     /* Separator for digit groups to left
                                         of radix character */
             char *grouping; /* Each element is the number of digits in a
                                group; elements with higher indices are
                                further left.  An element with value CHAR_MAX
                                means that no further grouping is done.  An
                                element with value 0 means that the previous
                                element is used for all groups further left. */

             /* Remaining fields are for monetary information */

             char *int_curr_symbol;   /* First three chars are a currency symbol
                                         from ISO 4217.  Fourth char is the
                                         separator.  Fifth char is '\0'. */
             char *currency_symbol;   /* Local currency symbol */
             char *mon_decimal_point; /* Radix character */
             char *mon_thousands_sep; /* Like thousands_sep above */
             char *mon_grouping;      /* Like grouping above */
             char *positive_sign;     /* Sign for positive values */
             char *negative_sign;     /* Sign for negative values */
             char  int_frac_digits;   /* International fractional digits */
             char  frac_digits;       /* Local fractional digits */
             char  p_cs_precedes;     /* 1 if currency_symbol precedes a
                                         positive value, 0 if succeeds */
             char  p_sep_by_space;    /* 1 if a space separates currency_symbol
                                         from a positive value */
             char  n_cs_precedes;     /* 1 if currency_symbol precedes a
                                         negative value, 0 if succeeds */
             char  n_sep_by_space;    /* 1 if a space separates currency_symbol
                                         from a negative value */
             /* Positive and negative sign positions:
                0 Parentheses surround the quantity and currency_symbol.
                1 The sign string precedes the quantity and currency_symbol.
                2 The sign string succeeds the quantity and currency_symbol.
                3 The sign string immediately precedes the currency_symbol.
                4 The sign string immediately succeeds the currency_symbol. */
             char  p_sign_posn;
             char  n_sign_posn;
         };

   POSIX.1-2008 extensions to the locale API
       POSIX.1-2008 standardized a number of extensions  to  the  locale  API,
       based  on implementations that first appeared in version 2.3 of the GNU
       C library.  These extensions are designed to address the  problem  that
       the traditional locale APIs do not mix well with multithreaded applica-
       tions and with applications that must deal with multiple locales.

       The extensions take the form of new functions for creating and  manipu-
       lating  locale  objects (newlocale(3), freelocale(3), duplocale(3), and
       uselocale(3)) and various new library functions with  the  suffix  "_l"
       (e.g.,  toupper_l(3)) that extend the traditional locale-dependent APIs
       (e.g., toupper(3)) to allow the specification of a locale  object  that
       should apply when executing the function.

ENVIRONMENT
       The  following  environment variable is used by newlocale(3) and setlo-
       cale(3), and thus affects all unprivileged localized programs:

       LOCPATH
              A list of pathnames, separated by colons (':'), that  should  be
              used  to  find  locale  data.  If this variable is set, only the
              individual compiled locale data files from LOCPATH and the  sys-
              tem  default locale data path are used; any available locale ar-
              chives are not used (see localedef(1)).  The individual compiled
              locale  data  files  are searched for under subdirectories which
              depend  on  the  currently  used  locale.   For  example,   when
              en_GB.UTF-8 is used for a category, the following subdirectories
              are searched for, in this order: en_GB.UTF-8, en_GB.utf8, en_GB,
              en.UTF-8, en.utf8, and en.

FILES
       /usr/lib/locale/locale-archive
              Usual default locale archive location.

       /usr/lib/locale
              Usual default path for compiled individual locale files.

CONFORMING TO
       POSIX.1-2001.

SEE ALSO
       iconv(1),  locale(1),  localedef(1),  catopen(3), gettext(3), iconv(3),
       localeconv(3), mbstowcs(3), newlocale(3), ngettext(3),  nl_langinfo(3),
       rpmatch(3),    setlocale(3),   strcoll(3),   strfmon(3),   strftime(3),
       strxfrm(3), uselocale(3),  wcstombs(3),  locale(5),  charsets(7),  uni-
       code(7), utf-8(7)

COLOPHON
       This  page  is  part of release 4.04 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
       http://www.kernel.org/doc/man-pages/.

Linux                             2015-07-23                         LOCALE(7)