PHP Regex patterns

file.php

<?php

// Remove attributes of HTML tag
$data = preg_replace("/<([a-z][a-z0-9]*)[^>]*?(\/?)>/i",'<$1$2>', $data); 

// Remove empty HTML tag
$data = preg_replace('#<([^ >]+)[^>]*>([[:space:]]|&nbsp;)*</\1>#', '', $data); 

// Remove non unicode character
$data = preg_replace('/[^\00-\255]+/u', '', $data); 

// Replace multiple space with single
$data = preg_replace("/[\pZ\pC]+/u", " ", $data);