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NL_LANGINFO(3P) POSIX Programmer's Manual NL_LANGINFO(3P)
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.
nl_langinfo, nl_langinfo_l — language information
#include <langinfo.h>
char *nl_langinfo(nl_item item);
char *nl_langinfo_l(nl_item item, locale_t locale);
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.
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().
No errors are defined.
The following sections are informative.
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);
...
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.
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.
None.
setlocale(3p), uselocale(3p)
The Base Definitions volume of POSIX.1‐2008, Chapter 7, Locale,
langinfo.h(0p), locale.h(0p), nl_types.h(0p)
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 .
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.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 NL_LANGINFO(3P)
Pages that refer to this page: langinfo.h(0p), nl_types.h(0p), localeconv(3p), setlocale(3p)