<?php
$test = "<code><b>PHP's really fun!</b></code>";
 
echo preg_replace('/\<code>(.+?)\<\/code\>/ies', "modify('\\1')", $test);
 
function modify($code) {
  $code = str_replace('\"', '"', $code); // undoes odd preg_replace() quirk of performing addslashes()
  $code = htmlentities($code); // makes safe for browser to display
return ($code);
}
?>