- var_dump: documentation ( source)
- preg_replace: documentation ( source)
- strtolower: documentation ( source)
<?php
$tests = array(
'abcdef',
'abc.fff.com',
'bla@mail.com',
'suikoden108',
);
foreach ( $tests as $name)
var_dump(strtolower(preg_replace('/[^A-Za-z0-9?!]/','', $name)));