平成30/ 2018-12-19 17:41
PHP 配列 list
$birthday = preg_split("/ +/u", $dt["birthday"]);
list($y, $m, $d) = preg_split("/-/u", $birthday[0]);
$dt["birthday"] = "{$y}年{$m}月{$d}日";

(Thanks.)
http://www.phppro.jp/phpmanual/php/function.list.html