newlocale, freelocale - create, modify, and free a locale object
#include <locale.h>
locale_t newlocale(int category_mask, const char *locale,
locale_t base);
void freelocale(locale_t locobj);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
newlocale(),
freelocale():
- Since glibc 2.10:
- _XOPEN_SOURCE >= 700
- Before glibc 2.10:
- _GNU_SOURCE
The
newlocale() function creates a new locale object, or modifies an
existing object, returning a reference to the new or modified object as the
function result. Whether the call creates a new object or modifies an existing
object is determined by the value of
base:
- *
- If base is (locale_t) 0, a new object is
created.
- *
- If base refers to valid existing locale object (i.e., an object
returned by a previous call to newlocale() or duplocale(3)),
then that object is modified by the call. If the call is successful, the
contents of base are unspecified (in particular, the object
referred to by base may be freed, and a new object created).
Therefore, the caller should ensure that it stops using base before
the call to newlocale(), and should subsequently refer to the
modified object via the reference returned as the function result. If the
call fails, the contents of base remain valid and unchanged.
If
base is the special locale object
LC_GLOBAL_LOCALE (see
duplocale(3)), or is not
(locale_t) 0 and is not a valid
locale object handle, the behavior is undefined.
The
category_mask argument is a bit mask that specifies the locale
categories that are to be set in a newly created locale object or modified in
an existing object. The mask is constructed by a bitwise OR of the constants
LC_ADDRESS_MASK,
LC_CTYPE_MASK,
LC_COLLATE_MASK,
LC_IDENTIFICATION_MASK,
LC_MEASUREMENT_MASK,
LC_MESSAGES_MASK,
LC_MONETARY_MASK,
LC_NUMERIC_MASK,
LC_NAME_MASK,
LC_PAPER_MASK,
LC_TELEPHONE_MASK, and
LC_TIME_MASK. Alternatively, the mask can be specified as
LC_ALL_MASK, which is equivalent to ORing all of the preceding
constants.
For each category specified in
category_mask, the locale data from
locale will be used in the object returned by
newlocale(). If a
new locale object is being created, data for all categories not specified in
category_mask is taken from the default ("POSIX") locale.
The following preset values of
locale are defined for all categories that
can be specified in
category_mask:
- "POSIX"
- A minimal locale environment for C language programs.
- "C"
- Equivalent to "POSIX".
- ""
- An implementation-defined native environment corresponding to the values
of the LC_* and LANG environment variables (see
locale(7)).
The
freelocale() function deallocates the resources associated with
locobj, a locale object previously returned by a call to
newlocale() or
duplocale(3). If
locobj is
LC_GLOBAL_LOCALE or is not valid locale object handle, the results are
undefined.
Once a locale object has been freed, the program should make no further use of
it.
On success,
newlocale() returns a handle that can be used in calls to
duplocale(3),
freelocale(), and other functions that take a
locale_t argument. On error,
newlocale() returns
(locale_t) 0, and sets
errno to indicate the cause of the
error.
- EINVAL
- One or more bits in category_mask do not correspond to a valid
locale category.
- EINVAL
- locale is NULL.
- ENOENT
- locale is not a string pointer referring to a valid locale.
- ENOMEM
- Insufficient memory to create a locale object.
The
newlocale() and
freelocale() functions first appeared in
version 2.3 of the GNU C library.
POSIX.1-2008.
Each locale object created by
newlocale() should be deallocated using
freelocale().
The program below takes up to two command-line arguments, which each identify
locales. The first argument is required, and is used to set the
LC_NUMERIC category in a locale object created using
newlocale(). The second command-line argument is optional; if it is
present, it is used to set the
LC_TIME category of the locale object.
Having created and initialized the locale object, the program then applies it
using
uselocale(3), and then tests the effect of the locale changes by:
- 1.
- Displaying a floating-point number with a fractional part. This output
will be affected by the LC_NUMERIC setting. In many
European-language locales, the fractional part of the number is separated
from the integer part using a comma, rather than a period.
- 2.
- Displaying the date. The format and language of the output will be
affected by the LC_TIME setting.
The following shell sessions show some example runs of this program.
Set the
LC_NUMERIC category to
fr_FR (French):
$ ./a.out fr_FR
123456,789
Fri Mar 7 00:25:08 2014
Set the
LC_NUMERIC category to
fr_FR (French), and the
LC_TIME category to
it_IT (Italian):
$ ./a.out fr_FR it_IT
123456,789
ven 07 mar 2014 00:26:01 CET
Specify the
LC_TIME setting as an empty string, which causes the value to
be taken from environment variable settings (which, here, specify
mi_NZ, New Zealand Māori):
$ LC_ALL=mi_NZ ./a.out fr_FR ""
123456,789
Te Paraire, te 07 o Poutū-te-rangi, 2014 00:38:44 CET
#define _XOPEN_SOURCE 700
#include <stdio.h>
#include <stdlib.h>
#include <locale.h>
#include <time.h>
#define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \
} while (0)
int
main(int argc, char *argv[])
{
char buf[100];
time_t t;
size_t s;
struct tm *tm;
locale_t loc, nloc;
if (argc < 2) {
fprintf(stderr, "Usage: %s locale1 [locale2]\n", argv[0]);
exit(EXIT_FAILURE);
}
/* Create a new locale object, taking the LC_NUMERIC settings
from the locale specified in argv[1] */
loc = newlocale(LC_NUMERIC_MASK, argv[1], (locale_t) 0);
if (loc == (locale_t) 0)
errExit("newlocale");
/* If a second command-line argument was specified, modify the
locale object to take the LC_TIME settings from the locale
specified in argv[2]. We assign the result of this newlocale()
call to 'nloc' rather than 'loc', since in some cases, we might
want to preserve 'loc' if this call fails. */
if (argc > 2) {
nloc = newlocale(LC_TIME_MASK, argv[2], loc);
if (nloc == (locale_t) 0)
errExit("newlocale");
loc = nloc;
}
/* Apply the newly created locale to this thread */
uselocale(loc);
/* Test effect of LC_NUMERIC */
printf("%8.3f\n", 123456.789);
/* Test effect of LC_TIME */
t = time(NULL);
tm = localtime(&t);
if (tm == NULL)
errExit("time");
s = strftime(buf, sizeof(buf), "%c", tm);
if (s == 0)
errExit("strftime");
printf("%s\n", buf);
/* Free the locale object */
freelocale(loc);
exit(EXIT_SUCCESS);
}
locale(1),
duplocale(3),
setlocale(3),
uselocale(3),
locale(5),
locale(7)