Set locale information

# setlocale

(PHP 4, PHP 5, PHP 7, PHP 8)

setlocale — Set locale information

### Description

setlocale(int `$category`, ?string `$locales`, string `...$rest`): string|false

Alternative signature (not supported with named arguments):

setlocale(int `$category`, array `$locale_array`): string|false

Sets locale information.

Warning

The locale information is maintained per process, not per thread. If you are running PHP on a multithreaded server API , you may experience sudden changes in locale settings while a script is running, though the script itself never called setlocale(). This happens due to other scripts running in different threads of the same process at the same time, changing the process-wide locale using setlocale(). On Windows, locale information is maintained per thread as of PHP 7.0.5.

### Parameters

`category`

  `category` is a named constant specifying the category of the functions affected by the locale setting:

  - `LC_ALL` for all of the below
  - `LC_COLLATE` for string comparison, see strcoll()
  - `LC_CTYPE` for character classification and conversion, for example ctype_alpha()
  - `LC_MONETARY` for localeconv()
  - `LC_NUMERIC` for decimal separator (See also localeconv())
  - `LC_TIME` for date and time formatting with strftime()
  - `LC_MESSAGES` for system responses (available if PHP was compiled with `libintl`)
`locales`

  If `locales` is the empty string `""` or is `null`, the locale names will be set from the values of environment variables with the same names as the above categories, or from "LANG".

  If `locales` is `"0"`, the locale setting is not affected, only the current setting is returned.

  If `locales` is followed by additional parameters then each parameter is tried to be set as new locale until success. This is useful if a locale is known under different names on different systems or for providing a fallback for a possibly not available locale.

`rest`

  Optional string parameters to try as locale settings until success.

`locale_array`

  Each array element is tried to be set as new locale until success. This is useful if a locale is known under different names on different systems or for providing a fallback for a possibly not available locale.

> Note:

> On Windows, setlocale(LC_ALL, '') sets the locale names from the system's regional/language settings (accessible via Control Panel).

### Return Values

Returns the new current locale, or `false` if the locale functionality is not implemented on your platform, the specified locale does not exist or the category name is invalid.

An invalid category name also causes a warning message. Category/locale names can be found in » RFC 1766 and » ISO 639. Different systems have different naming schemes for locales.

> Note:

> The return value of setlocale() depends on the system that PHP is running. It returns exactly what the system `setlocale` function returns.

### Changelog

Version | Description
--- | ---
8.5.0 | Passing an integer `0` as the `locales` argument is no longer supported and now throws a TypeError.

### Examples

Example #1 setlocale() Examples

`<?php
/* Set locale to Dutch */
setlocale(LC_ALL, 'nl_NL');
/* Output: vrijdag 22 december 1978 */
echo strftime("%A %e %B %Y", mktime(0, 0, 0, 12, 22, 1978));
/* try different possible locale names for german */
$loc_de = setlocale(LC_ALL, 'de_DE@euro', 'de_DE', 'de', 'ge');
echo "Preferred locale for german on this system is '$loc_de'";
?>`

Example #2 setlocale() Retrieve current setting

`<?php
/* Retrieve current setting */
$current = setlocale(LC_ALL, null);
echo "Current locale '$current'";
?>`

Example #3 setlocale() Examples for Windows

`<?php
/* Set locale to Dutch */
setlocale(LC_ALL, 'nld_nld');
/* Output: vrijdag 22 december 1978 */
echo strftime("%A %d %B %Y", mktime(0, 0, 0, 12, 22, 1978));
/* try different possible locale names for german */
$loc_de = setlocale(LC_ALL, 'de_DE@euro', 'de_DE', 'deu_deu');
echo "Preferred locale for german on this system is '$loc_de'";
?>`

### Notes

Tip

Windows users will find useful information about `locales` strings at Microsoft's MSDN website. Supported language strings can be found in the » language strings documentation and supported country/region strings in the » country/region strings documentation.

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