(PHP 5 >= 5.3.0, PHP 7, PHP 8, PECL intl >= 1.0.0)
Locale::lookup -- locale_lookup — Searches the language tag list for the best match to the language
Object-oriented style
$languageTag,$locale,$canonicalize = false,$defaultLocale = nullProcedural style
$languageTag,$locale,$canonicalize = false,$defaultLocale = null
   Searches the items in languageTag for the best match to
   the language range specified in locale according to
   RFC 4647's lookup algorithm.
  
languageTag
       An array containing a list of language tags to compare to
       locale. Maximum 100 items allowed.
      
localeThe locale to use as the language range when matching.
canonicalize
       If true, the arguments will be converted to canonical form before matching.
defaultLocaleThe locale to use if no match is found.
The closest matching language tag or default value.
Returns null when the length of locale exceeds INTL_MAX_LOCALE_LEN.
| Version | Description | 
|---|---|
| 7.4.0 | defaultLocaleis nullable now. | 
Example #1 locale_lookup() example
<?php
$arr = array(
    'de-DEVA',
    'de-DE-1996',
    'de',
    'de-De'
);
echo locale_lookup($arr, 'de-DE-1996-x-prv1-prv2', true, 'en_US');
?>
Example #2 OO example
<?php
$arr = array(
    'de-DEVA',
    'de-DE-1996',
    'de',
    'de-De'
);
echo Locale::lookup($arr, 'de-DE-1996-x-prv1-prv2', true, 'en_US');
?>
The above example will output:
de_de_1996