Ora funziona!!Grazie mille per le dritte!!
<?
session_start();
$DEPOSITO=$_POST["DEPOSITO"];
require '../../config/includes_into.php';
$db=dbconnect();
function ValidateFloat($float) {
$val = htmlentities(strip_tags(trim($float)));
$val = str_replace(",", ".", str_replace(".", ""...