Ciao.
C'è qualcuno che mi spiega perchè se si
mette delle lettere accentate questo esempio
non funziona (funziona solo con FILTER_SANITIZE_STRING)
mentre in tutti gli esempi nel web è consigliato
l'uso di FILTER_SANITIZE_STRING,FILTER_FLAG_ENCODE_HIGH|FIL TER_FLAG_ENCODE_LOW

Esempio provare per credere

Codice PHP:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Untitled Document</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<?php 
if(filter_has_var(INPUT_POST'due')){
$name filter_input(INPUT_POST'uno',FILTER_SANITIZE_STRING);
echo 
'FILTER_SANITIZE_STRING :'.$name.'
'
;
$name filter_input(INPUT_POST'uno',FILTER_SANITIZE_STRING,FILTER_FLAG_ENCODE_HIGH|FILTER_FLAG_ENCODE_LOW);
echo 
'FILTER_SANITIZE_STRING,FILTER_FLAG_ENCODE_HIGH|FILTER_FLAG_ENCODE_LOW :'.$name.'
'
;
$name filter_input(INPUT_POST'uno',FILTER_SANITIZE_STRING,FILTER_FLAG_STRIP_LOW|FILTER_FLAG_STRIP_HIGH);
echo 
'FILTER_SANITIZE_STRING,FILTER_FLAG_STRIP_LOW|FILTER_FLAG_STRIP_HIGH :'.$name.'
'
;
}
?>
<form action="test.php" method="post">
<input name="uno" type="text">

<input name="due" type="submit" value="send">
</form>
</body>
</html>