- preg_match: documentation ( source)
<?php
echo "---------------------password check----------------------- \n";
$str1="JamesBlunt32";
if(preg_match("/\A(?=\w{6,12}\z)(?=[^a-z]*[a-z])(?:[^A-Z]*[A-Z])(\D*\d.*)\z/", $str1)==1){
echo "Password valid \n";
}
else echo "Password invalid \n";