$re = '/^
(?> #MAIN iteration (atomic only for efficiency)
(?<upper>[A-Z]) # an uppercase letter
| # or
(?<lower>[a-z]) # a lowercase letter
| # or
(?<digit>[0-9]) # a digit
| # or
(?<special>[^(0-9|a-z|A-Z)]) # a special
| # or
. # anything else
){10,15}? #REPEATED 8+ times
#
#CONDITIONS:
(?(upper) # 1. There must be at least 1 uppercase
(?(lower) # 2. If (1), there must be 1 lowercase
(?(digit) # 3. If (2), there must be 1 digit
(?(special)
# must be 1 special
| (?!) # Else fail
) #
| (?!) # Else fail
) #
| (?!) # Else fail
) #
| (?!) # Else fail
) $ #/x';
$str = '1ffdA$@3d3sd$f';
preg_match($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