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 ALSOsetlocale(), 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)
