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.
The duplocale() function shall create a duplicate copy of the locale
object referenced by the locobj argument.
If the locobj argument is LC_GLOBAL_LOCALE, duplocale() shall create
a new locale object containing a copy of the global locale determined
by the setlocale() function.
The behavior is undefined if the locobj argument is not a valid
locale object handle.
Constructing an Altered Version of an Existing Locale Object
The following example shows a code fragment to create a slightly
altered version of an existing locale object. The function takes a
locale object and a locale name and it replaces the LC_TIME category
data in the locale object with that from the named locale.
with_changed_lc_time (locale_t obj, const char *name)
locale_t retval = duplocale (obj);
if (retval != (locale_t) 0)
locale_t changed = newlocale (LC_TIME_MASK, name, retval);
if (changed == (locale_t) 0)
/* An error occurred. Free all allocated resources. */
retval = changed;
return retval; }
The use of the duplocale() function is recommended for situations
where a locale object is being used in multiple places, and it is
possible that the lifetime of the locale object might end before all
uses are finished. Another reason to duplicate a locale object is if
a slightly modified form is needed. This can be achieved by a call
to newlocale() following the duplocale() call.
As with the newlocale() function, handles for locale objects created
by the duplocale() function should be released by a corresponding
call to freelocale().
The duplocale() function can also be used in conjunction with
uselocale((locale_t)0). This returns the locale in effect for the
calling thread, but can have the value LC_GLOBAL_LOCALE. Passing
LC_GLOBAL_LOCALE to functions such as isalnum_l() results in
undefined behavior, but applications can convert it into a usable
locale object by using duplocale().
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
IEEE/The Open Group 2013 DUPLOCALE(3P)