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DUPLOCALE(3) | Linux Programmer's Manual | 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¶
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2017-09-15 | Linux |