prova così:
codice:
<?php
if(isset($_POST['invia']))
{
switch ($_POST['operation'])
{
case "+":
$x = $_POST['num1'] + $_POST['num2'];
break;
case "-":
$x = $_POST['num1'] - $_POST['num2'];
break;
case "*":
$x = $_POST['num1'] * $_POST['num2'];
break;
case "/":
$x = $_POST['num1'] / $_POST['num2'];
break;
default:
break;
}
}
?>
</h2>
</td></tr></table>
<form action=" <?PHP echo $_SERVER['PHP_SELF']?>" method="post">
<table><tr>
</td><tr><td>Operando 1</td><td>
<input type="text" name="num1" value=""></td>
<td rowspan=2>
<input type="radio" name="operation" value="+">+
<input type="radio" name="operation" value="-">-
<input type="radio" name="operation" value="*">*
<input type="radio" name="operation" value="/">/
</td></tr>
<tr><td> Operando 2 </td><td>
<input type="text" name="num2" value=""></td></tr>
<tr><td><input type=submit name="invia" value="Calcola"></td>
<td colspan=2 align=center>
<?PHP
if(isset($_POST['invia']))
echo $_POST['num1']." ".$_POST['operation']." ".$_POST['num2']." = ".$x; ?>
<td><tr>
</table>
</form>
ciao