- preg_match: documentation ( source)
<?php
$pswd = "Ap";
$specialChar= preg_match("/(?=.*[!@#&*%]+)/", $pswd); // at least one
$numberChar= preg_match("/(?=.*\d){2,}/", $pswd); //two or more digits
$upperChar= preg_match("/(?=.*[A-Z]){2,}/", $pswd); //two or more upper case letters
$lowerChar= preg_match("/(?=.*[a-z]){2,}/", $pswd); //two or more lower case letters
$pswdLength = preg_match("/(?=^.{6,20}$)/", $pswd); //length of pswd between min and max
echo $specialChar . " " . $numberChar . " " . $upperChar . " " . $lowerChar . " " . $pswdLength;