DUPLOCALE(3P)              POSIX Programmer's Manual             DUPLOCALE(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
       duplocale -- duplicate a locale object

SYNOPSIS
       #include <locale.h>

       locale_t duplocale(locale_t locobj);

DESCRIPTION
       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.

RETURN VALUE
       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.

ERRORS
       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.

EXAMPLES
   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.


           #include <locale.h>
           ...

           locale_t
           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. */
                       freelocale (retval);
                   retval = changed;
               }
               return retval;
           }

APPLICATION USAGE
       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().

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       freelocale(), newlocale(), uselocale()

       The Base Definitions volume of POSIX.1-2017, <locale.h>

COPYRIGHT
       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                        DUPLOCALE(3P)