duplocale - duplicate a locale object


   #include <locale.h>

   locale_t duplocale(locale_t locobj);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       Since glibc 2.10:
              _XOPEN_SOURCE >= 700
       Before glibc 2.10:


   The  duplocale()  function  creates  a  duplicate  of the locale object
   referred to by locobj.

   If locobj is LC_GLOBAL_LOCALE,  duplocale()  creates  a  locale  object
   containing a copy of the global locale determined by setlocale(3).


   On success, duplocale() returns a handle for the new locale object.  On
   error, it returns (locale_t) 0, and sets errno to indicate the cause of
   the error.


   ENOMEM Insufficient memory to create the duplicate locale object.


   The  duplocale()  function  first  appeared in version 2.3 of the GNU C




   Duplicating a locale can serve the following purposes:

   *  To create a copy of a locale object in which one of more  categories
      are to be modified (using newlocale(3)).

   *  To  obtain  a  handle for the current locale which can used in other
      functions that employ a locale handle, such as  toupper_l(3).   This
      is  done  by  applying  duplocale()  to  the  value  returned by the
      following call:

          loc = uselocale((locale_t) 0);

      This technique is necessary, because the above uselocale(3) call may
      return  the  value  LC_GLOBAL_LOCALE,  which  results  in  undefined
      behavior if passed  to  functions  such  as  toupper_l(3).   Calling
      duplocale() can be used to ensure that the LC_GLOBAL_LOCALE value is
      converted into a usable locale object.  See EXAMPLE, below.

   Each locale object created by duplocale() should be  deallocated  using


   The  program below uses uselocale(3) and duplocale() to obtain a handle
   for the current locale which  is  then  passed  to  toupper_l(3).   The
   program takes one command-line argument, a string of characters that is
   converted to uppercase and displayed on standard output.  An example of
   its use is the following:

       $ ./a.out abc

   Program source
   #define _XOPEN_SOURCE 700
   #include <ctype.h>
   #include <stdio.h>
   #include <stdlib.h>
   #include <locale.h>

   #define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \
                           } while (0)

   main(int argc, char *argv[])
       locale_t loc, nloc;
       char *p;

       if (argc != 2) {
           fprintf(stderr, "Usage: %s string\n", argv[0]);

       /* This sequence is necessary, because uselocale() might return
          the value LC_GLOBAL_LOCALE, which can't be passed as an
          argument to toupper_l() */

       loc = uselocale((locale_t) 0);
       if (loc == (locale_t) 0)

       nloc = duplocale(loc);
       if (nloc == (locale_t) 0)

       for (p = argv[1]; *p; p++)
           putchar(toupper_l(*p, nloc));





   freelocale(3),  newlocale(3),  setlocale(3),  uselocale(3),  locale(5),


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