NAME | SYNOPSIS | DESCRIPTION | ENVIRONMENT | CONFORMING TO | SEE ALSO | COLOPHON

LOCALE(7)                 Linux Programmer's Manual                LOCALE(7)

NAME         top

       locale - description of multilanguage support

SYNOPSIS         top

       #include <locale.h>

DESCRIPTION         top

       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_langinfo(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
              language 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.  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_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-
              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
              displayed 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
              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_MEASUREMENT_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
              persons.  Applications that need this information can use
              nl_langinfo(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
              nonmonetary numeric values—for example, the thousands
              separator and the radix character (a period in most English-
              speaking countries, 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
              telephone 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
              numbers 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
              values.  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 strftime(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
              categories 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
       applications and with applications that must deal with multiple
       locales.

       The extensions take the form of new functions for creating and
       manipulating 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         top

       The following environment variable is used by newlocale(3) and
       setlocale(3), and thus affects all 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 locale data files from LOCPATH and the system
              default locale data path are used; any available locale
              archives are not used. The individual locale data files are
              searched 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.

CONFORMING TO         top

       POSIX.1-2001.

SEE ALSO         top

       locale(1), localedef(1), catopen(3), gettext(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), unicode(7),
       utf-8(7)

COLOPHON         top

       This page is part of release 3.71 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                            2014-05-28                        LOCALE(7)