$re = '/^(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.*[^\s])[A-Za-z\d^\s]{8,}$/';
$str = 'Blablabla
Bj4
Vj4kl4kzgf9G
VjklkzgfG
VjklkzgfG_
Blablabla4
blablabla4
bdasDSADAsd';
preg_match_all($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