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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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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(). The returned pointer and the string content
might also be invalidated if the calling thread is terminated.
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.1‐2017, 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 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. 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.opengroup.org/unix/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 2017 NL_LANGINFO(3P)
Pages that refer to this page: langinfo.h(0p), nl_types.h(0p), localeconv(3p), setlocale(3p)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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