$re = '/^user\/[0-9A-F]{8}-[0-9A-F]{4}-[4][0-9A-F]{3}-[89AB][0-9A-F]{3}-[0-9A-F]{12}(?:\/.*)?$/im';
$str = 'user/a24a6ea4-ce75-4665-a070-57453082c256
user/a24a6ea4-ce75-4665-a070-57453082c256/photo
user/a24a6ea4-ce75-4665-a070-57453082c256asdasd';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php