Codice PHP:
$search = array ("'<script[^>]*?>.*?</script>'si",  // Strip out javascript
                 "'<[\/\!]*?[^<>]*?>'si",           // Strip out HTML tags
                 "'([\r\n])[\s]+'",                 // Strip out white space
                 "'&(quot|#34);'i",                 // Replace HTML entities
                 "'&(amp|#38);'i",
                 "'&(lt|#60);'i",
                 "'&(gt|#62);'i",
                 "'&(nbsp|#160);'i",
                 "'&(iexcl|#161);'i",
                 "'&(cent|#162);'i",
                 "'&(pound|#163);'i",
                 "'&(copy|#169);'i",
                 "'&#(\d+);'e");                    // evaluate as php

                 $replace = array ("",
                  "",
                  "\\1",
                  "\"",
                  "&",
                  "<",
                  ">",
                  " ",
                  chr(161),
                  chr(162),
                  chr(163),
                  chr(169),
                  "chr(\\1)");


$testo=    <a href=http://esempio.html>ciao</a>";




$messaggio = preg_replace($search, $replace, $testo);
echo $messaggio;