DUPLOCALE(3P) POSIX Programmer's Manual DUPLOCALE(3P)PROLOG
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NAMEduplocale — duplicate a locale object
locale_t duplocale(locale_t locobj);
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
Upon successful completion, the duplocale() function shall return a
handle for a new locale object. Otherwise, duplocale() shall return
(locale_t)0 and set errno to indicate the error.
The duplocale() function shall fail if:
ENOMEM There is not enough memory available to create the locale object
or load the locale data.
The following sections are informative.
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
The duplocale() function can also be used in conjunction with uselo‐
cale((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().
SEE ALSOfreelocale(), newlocale(), uselocale()
The Base Definitions volume of POSIX.1‐2008, <locale.h>
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 .
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IEEE/The Open Group 2013 DUPLOCALE(3P)