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NL_LANGINFO(3P)            POSIX Programmer's Manual           NL_LANGINFO(3P)
PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       nl_langinfo, nl_langinfo_l -- language information
SYNOPSIS
       #include <langinfo.h>
       char *nl_langinfo(nl_item item);
       char *nl_langinfo_l(nl_item item, locale_t locale);
DESCRIPTION
       The nl_langinfo() and nl_langinfo_l() functions shall return a  pointer
       to  a string containing information relevant to the particular language
       or cultural area defined in the current locale, or in the locale repre-
       sented  by  locale, respectively (see <langinfo.h>).  The manifest con-
       stant names and values of item are defined in <langinfo.h>.  For  exam-
       ple:
           nl_langinfo(ABDAY_1)
       would  return  a pointer to the string "Dom" if the identified language
       was Portuguese, and "Sun" if the identified language was English.
           nl_langinfo_l(ABDAY_1, loc)
       would return a pointer to the string "Dom" if the  identified  language
       of the locale represented by loc was Portuguese, and "Sun" if the iden-
       tified language of the locale represented by loc was English.
       The nl_langinfo() function need not be thread-safe.
       The behavior is undefined if the locale argument to nl_langinfo_l()  is
       the  special  locale  object  LC_GLOBAL_LOCALE or is not a valid locale
       object handle.
RETURN VALUE
       In a locale where langinfo data is not defined, these  functions  shall
       return  a  pointer  to the corresponding string in the POSIX locale. In
       all locales, these functions shall return a pointer to an empty  string
       if item contains an invalid setting.
       The  application  shall  not  modify  the  string returned. The pointer
       returned by nl_langinfo() might be invalidated or  the  string  content
       might  be  overwritten  by  a  subsequent  call to nl_langinfo() in any
       thread or to nl_langinfo_l() in the same thread or the initial  thread,
       by subsequent calls to setlocale() with a category corresponding to the
       category of item (see <langinfo.h>) or the category LC_ALL, or by  sub-
       sequent calls to uselocale() which change the category corresponding to
       the category of item.  The pointer returned by nl_langinfo_l() might be
       invalidated  or the string content might be overwritten by a subsequent
       call to nl_langinfo_l() in the same thread or to nl_langinfo()  in  any
       thread,  or  by  subsequent  calls to freelocale() or newlocale() which
       free or modify the locale object that was passed to nl_langinfo_l().
ERRORS
       No errors are defined.
       The following sections are informative.
EXAMPLES
   Getting Date and Time Formatting Information
       The following example returns a pointer to a string containing date and
       time  formatting information, as defined in the LC_TIME category of the
       current locale.
           #include <time.h>
           #include <langinfo.h>
           ...
           strftime(datestring, sizeof(datestring), nl_langinfo(D_T_FMT), tm);
           ...
APPLICATION USAGE
       The array pointed to by the return value should not be modified by  the
       program, but may be modified by further calls to these functions.
RATIONALE
       The  possible  interactions between internal data used by nl_langinfo()
       and nl_langinfo_l() are complicated by the  fact  that  nl_langinfo_l()
       must  be  thread-safe but nl_langinfo() need not be. The various imple-
       mentation choices are:
        1. nl_langinfo_l() and nl_langinfo() use separate buffers, or at least
           one  of  them  does not use an internal string buffer. In this case
           there are no interactions.
        2. nl_langinfo_l() and nl_langinfo() share an internal per-thread buf-
           fer. There can be interactions, but only in the same thread.
        3. nl_langinfo_l()  uses  an  internal per-thread buffer, and nl_lang-
           info() uses (in all threads) the same buffer  that  nl_langinfo_l()
           uses  in  the  initial  thread. There can be interactions, but only
           when nl_langinfo_l() is called in the initial thread.
FUTURE DIRECTIONS
       None.
SEE ALSO
       setlocale(), uselocale()
       The Base Definitions volume of POSIX.1-2008, Chapter 7, Locale,  <lang-
       info.h>, <locale.h>, <nl_types.h>
COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.unix.org/online.html .
       Any typographical or formatting errors that appear  in  this  page  are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors,  see  https://www.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                      NL_LANGINFO(3P)