setlocale(3) — Linux manual page


SETLOCALE(3)              Linux Programmer's Manual             SETLOCALE(3)

NAME         top

       setlocale - set the current locale

SYNOPSIS         top

       #include <locale.h>

       char *setlocale(int category, const char *locale);

DESCRIPTION         top

       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

       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

           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         top

       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         top

       For an explanation of the terms used in this section, see

       │Interface   Attribute     Value                      │
       │setlocale() │ Thread safety │ MT-Unsafe const:locale env │

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008, C89, C99.

       The C standards specify only the categories LC_ALL, LC_COLLATE,
       LC_MESSAGES.  The remaining categories are GNU extensions.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.08 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

GNU                              2017-09-15                     SETLOCALE(3)

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