(PHP 5.5.0, PECL >= 3.0.0a1)
IntlCalendar::getLocale — Get the locale associated with the object
Object oriented style
$localeType
   )Procedural style
Returns the locale used by this calendar object.
calThe IntlCalendar resource.
localeType
      Whether to fetch the actual locale (the locale from which the calendar
      data originates, with Locale::ACTUAL_LOCALE) or the
      valid locale, i.e., the most specific locale supported by ICU relatively
      to the requested locale – see Locale::VALID_LOCALE.
      From the most general to the most specific, the locales are ordered in
      this fashion – actual locale, valid locale, requested locale.
     
   A locale string or FALSE on failure.
  
Example #1 IntlCalendar::getLocale()
<?php
$cal = IntlCalendar::createInstance(IntlTimeZone::getGMT(), 'en_US_CALIFORNIA');
var_dump(
    $cal->getLocale(Locale::ACTUAL_LOCALE),
    $cal->getLocale(Locale::VALID_LOCALE)
);
The above example will output:
string(2) "en" string(5) "en_US"