locale(7)



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 ad-
              dresses) used to describe locations and geography-related items.
              Applications  that  need this information can use nl_langinfo(3)
              to retrieve  nonstandard  elements,  such  as  _NL_ADDRESS_COUN-
              TRY_NAME  (country  name,  in  the  language  of the locale) and
              _NL_ADDRESS_LANG_NAME (language name, in the language of the lo-
              cale),  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.  Ap-
              plications that need this information can use nl_langinfo(3)  to
              retrieve  nonstandard elements, such as _NL_IDENTIFICATION_TITLE
              (title of this locale document) and _NL_IDENTIFICATION_TERRITORY
              (geographical  territory to which this locale document 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-re-
              lated 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  rp-
              match(3) functions to ease the use of this information.  The GNU
              gettext family of functions also obey the  environment  variable
              LANGUAGE  (containing  a colon-separated list of locales) if the
              category is set to a valid locale other than "C".  This category
              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  re-
              trieve the nonstandard _NL_PAPER_WIDTH and _NL_PAPER_HEIGHT ele-
              ments, which return int values specifying the dimensions in mil-
              limeters.

       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  cate-
          gories above exists and is non-null, its value is used for that cat-
          egory.

       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 in-
              dividual  compiled locale data files from LOCPATH and the system
              default locale data path are used; any available locale archives
              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
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       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/.

Linux                             2017-09-15                         LOCALE(7)

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