taking care of XSS

echo htmlentities($_POST[‘input’], ENT_QUOTES, ‘UTF-8’);

array_walk($_POST, 'htmlentities');

function h($s) { echo(htmlspecialchars($s)); }
...
<?php h($POST['input']) ?>

$_POST = clean_input($_POST);
$_GET = clean_input($_GET);
$_COOKIE = clean_input($_COOKIE);
$_SESSION = clean_input($_SESSION);

function clean_input($array){
    if(count($array)){
    	foreach ($array as $key => $value) {
    		$array[$key]=htmlentities($value, ENT_QUOTES, 'UTF-8');
    	}
    }
    return $array;
}