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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | NOTES | EXAMPLES | SEE ALSO | COLOPHON |
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newlocale(3) Library Functions Manual newlocale(3)
newlocale, freelocale - create, modify, and free a locale object
Standard C library (libc, -lc)
#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)).
freelocale()
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 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.
POSIX.1-2008.
glibc 2.3.
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
Program source
#define _XOPEN_SOURCE 700
#include <locale.h>
#include <stdio.h>
#include <stdlib.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. */
uselocale(LC_GLOBAL_LOCALE); /* So 'loc' is no longer in use */
freelocale(loc);
exit(EXIT_SUCCESS);
}
locale(1), duplocale(3), setlocale(3), uselocale(3), locale(5),
locale(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
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for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
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2025-08-11. If you discover any rendering problems in this HTML
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Linux man-pages 6.15 2025-05-17 newlocale(3)
Pages that refer to this page: duplocale(3), isalpha(3), locale_t(3type), nl_langinfo(3), toupper(3), uselocale(3), locale(5), locale(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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