$re = '/(?:[^a-zA-Z0-9]*[a-zA-Z0-9]){3}/';
$str = '+++++\' \'asd\'\'\'\'\'\'\'\'\'\'\'sdsdsdsdsdsddddddddddddddddddddddddddddddddd\'\'\'\' fdfdfdfdfddfdfdfdfdfdfdfdfdfdfdfdf\'\'sssdssssssssssssssssssssssssss\'\'\'\'\'sd\'\'\'\'\'\'\' d
\'\'\'\'\'\'\'\'\'\'\'\'\'sd\'\' sfdasdasd dsa sdk\' d\' ddaf 3f0 sc\'ddd\'_0_c_8_\'\' 9 9d \'c\'ddd\'_0_csdf
as 0a
_0_c_sdf8_
K9Jk0-asd
L________f______________3j
]\\[][]\\[';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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