perchè però mi dice undefined index?
PAGINA1
Codice PHP:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Documento senza titolo</title>
</head> <body>
 <form action="primo.php" method="post"> 
First name: <input type="text" name="fname" id="fname">

 Last name: <input type="text" name="lname" id="lname">
 <input type="submit" value="Submit"> </form> </body> </html> 
PAGINA 2
Codice PHP:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Documento senza titolo</title> </head> <body> 
<?php session_start();
 $fname = $_SESSION['fname'];
 $lname = $_SESSION['lname'];
 echo $fname; echo $lname; ?>
 <form action="terzo.php" method="post"> 
via: <input type="text" name="via">
 cisttà:
 <input type="text" name="citta">
 <input type="submit" value="Submit"> </form> </body> </html>
PAGINA3

Codice PHP:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 
<title>Documento senza titolo</title> </head> <body> <?php session_start();
 $fname = $_SESSION['fname']; 
$lname = $_SESSION['lname']; 
$via = $_SESSION['via']; 
$citta = $_SESSION['citta'];
 echo $fname; echo $lname;
 echo $via;
 echo $citta; ?> </body> </html>