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
       represented  by  locale, respectively (see <langinfo.h>).  The manifest constant names and values of item
       are defined in <langinfo.h>.  For example:

           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 identified 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
       subsequent  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
       implementation 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 buffer. There can be interactions, but
           only in the same thread.

        3. nl_langinfo_l()  uses an internal per-thread buffer, and nl_langinfo() 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, <langinfo.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 Electrical 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 .

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