php：表单定价错误[关闭]

Question

As you can see I am trying to create a simple form which outputs the price in the php part. But i get these errors

Notice: Undefined variable: result in /var/www/vhosts/numyspace.co.uk/web_users/home/~unn_w12024193/public_html/test/example2.php on line 3

Notice: Undefined index: booking in /var/www/vhosts/numyspace.co.uk/web_users/home/~unn_w12024193/public_html/test/example2.php on line 4

Warning: Division by zero in /var/www/vhosts/numyspace.co.uk/web_users/home/~unn_w12024193/public_html/test/example2.php on line 4

Total cost is: Notice: Undefined variable: result in /var/www/vhosts/numyspace.co.uk/web_users/home/~unn_w12024193/public_html/test/example2.php on line 18 exculding VAT. Total cost is including VAT.

HTML

<form method="post" action="example2.php">
<select name="booking">
<option value="Double Room">Double Room £50</option>
<option value="Twin Room">Twin Room £70</option>
<option value="Family Room">Family Room £100</option>
</select>

<select name="service">
 <option value="10">Yes £10</option>
 <option value="0">No</option>
</select>

<input type="submit" value="submit" action="example2.php" name="submit"><br />
</form>

PHP

$vresult = $result * 20%
$booking = $_GET["booking"];

if ($booking == "Double Room"){
$result = 50 + $_GET["service"];
}
else if($booking == "Twin Room"){
$result = 50 + $_GET["service"];
}
else if($booking == "Family Room"){
$result = 100 + $_GET["service"];
}
?>
 Total cost is <?php echo $result;?> exculding VAT.

 Total cost is <?php echo $vresult; ?> including VAT.

Answer 1

First: vresult should be after you defined $result, and calculate 20% extra with * 1.2 instead of * 20%; Second: You need to use $_POST instead of $_GET
Third: $_POST['service'] can be altered, just check it before you output it

$booking = @$_POST["booking"];
$service = @$_POST["service"] == 10? 10 : 0;

if ($booking == "Double Room"){
   $result = 50 + $service;
}
else if($booking == "Twin Room"){
   $result = 50 + $service;
}
else if($booking == "Family Room"){
   $result = 100 + $service;
}
$vresult = $result * 1.2;
?>
 Total cost is <?php echo $result;?> exculding VAT.

 Total cost is <?php echo $vresult; ?> including VAT.