Alternative signature (not supported with named arguments):stringfalsesetlocale intcategory arraylocale_array
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 strtoupper
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)
If locales is the empty string "", 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.
Optional string parameters to try as locale settings until success.
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.
On Windows, setlocale(LC_ALL, '') sets the locale names from the system's regional/language settings (accessible via Control Panel).
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.
The return value of setlocale depends on the system that PHP is running. It returns exactly what the system setlocale function returns.
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.