duplocale(3)
NAME
duplocale - duplicate a locale object
SYNOPSIS
#include <locale.h>
locale_t duplocale(locale_t locobj);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
duplocale():
Since glibc 2.10:
_XOPEN_SOURCE >= 700
Before glibc 2.10:
_GNU_SOURCE
DESCRIPTION
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).
RETURN VALUE
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.
ERRORS
ENOMEM Insufficient memory to create the duplicate locale object.
VERSIONS
The duplocale() function first appeared in version 2.3 of the GNU C library.
CONFORMING TO
POSIX.1-2008.
NOTES
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
freelocale(3).
EXAMPLE
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 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) int main(int argc, char *argv[]) { locale_t loc, nloc; char *p; if (argc != 2) { fprintf(stderr, "Usage: %s string\n", argv[0]); exit(EXIT_FAILURE); } /* 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) errExit("uselocale"); nloc = duplocale(loc); if (nloc == (locale_t) 0) errExit("duplocale"); for (p = argv[1]; *p; p++) putchar(toupper_l(*p, nloc)); printf("\n"); freelocale(nloc); exit(EXIT_SUCCESS); }
SEE ALSO
freelocale(3), newlocale(3), setlocale(3), uselocale(3), locale(5), locale(7)
COLOPHON
This page is part of release 4.09 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
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