function filter_string($string, $allowed_tags=[]) {
<br> //Potentially suitable for filtering data submitted via textarea.
<br>
<br> //remove HTML &amp; PHP tags (please read note above for more!)
<br> $string = strip_tags($string, $allowed_tags);
<br>
<br> // Apply XSS filtering
<br> $string = htmlspecialchars($string);
<br>
<br> // Convert multiple consecutive whitespaces to a single space, except for line breaks
<br> $string = preg_replace('/[^\S\r\n]+/', ' ', $string);
<br>
<br> // Trim leading and trailing white space
<br> $string = trim($string);
<br>
<br> return $string;
<br>}

$allowed_tags ='';
<br> //remove HTML &amp; PHP tags (please read note above for more!)
<br> $string = strip_tags($string, $allowed_tags);