PHP Forms checkbox calculation - php

Question

I am trying to perform some calculations with a form but every time i try to work with checkboxes it goes wrong.
The checkboxes are beign set on value 1 in the form itselff and are being checked if there checked or not.
$verdieping = isset($_POST["verdieping"]) ? $_POST["verdieping"] : 0;
$telefoon = isset($_POST["telefoon"]) ? $_POST["telefoon"] : 0;
$netwerk = isset($_POST["netwerk"]) ? $_POST["netwerk"] : 0;
When i try to do calculations every works expect for the options with the checkboxes.
When both checkboxes (telefoon & netwerk) are selected the value should be 30.
If only one is selected the value should be 20.
But no mather what i have tried to write down it always give problem, and it always uses 20, never the value 30.
How do i solve this problem? Or suppose i am writing the syntax all wrong to lay conditions to a calculation? Any input appreciated.
$standnaam = $_SESSION["standnaam"];
$oppervlakte = $_SESSION["oppervlakte"];
$verdieping = $_SESSION["verdieping"];
$telefoon = $_SESSION["telefoon"];
$netwerk = $_SESSION["netwerk"];
if ($oppervlakte <= 10)
$tarief = 100;
if ($oppervlakte > 10 && $oppervlakte <= 20)
$tarief = 90;
if ($oppervlakte > 20)
$tarief = 80;
if($verdieping == 1)
{
$prijsVerdieping = $oppervlakte * 120;
}
else
{
$prijsVerdieping = 0;
}
if(($telefoon == 1) && ($netwerk == 1))
{
$prijsCom = 30; // never get this value, it always uses 20
}
if(($telefoon == 1) || ($netwerk == 1))
{
$prijsCom = 20;
}
$prijsOpp = $tarief * $oppervlakte; // works
$totalePrijs = $prijsOpp + $prijsVerdieping + $prijsCom; //prijsCom value is always wrong
Regards.
EDIT: full code below in 2 php files
<?php
if (!empty($_POST))
{
$standnaam = $_POST["standnaam"];
$oppervlakte = $_POST["oppervlakte"];
//value in the form van checkboxes op 1 zetten!
$verdieping = isset($_POST["verdieping"]) ? $_POST["verdieping"] : 0; //if checkbox checked value 1 anders 0
$telefoon = isset($_POST["telefoon"]) ? $_POST["telefoon"] : 0;
$netwerk = isset($_POST["netwerk"]) ? $_POST["netwerk"] : 0;
if (is_numeric($oppervlakte))
{
$_SESSION["standnaam"]=$standnaam;
$_SESSION["oppervlakte"]=$oppervlakte;
$_SESSION["verdieping"]=$verdieping;
$_SESSION["telefoon"]=$telefoon;
$_SESSION["netwerk"]=$netwerk;
header("Location:ExpoOverzicht.php"); //verzenden naar ExpoOverzicht.php
}
else
{
echo "<h1>Foute gegevens, Opnieuw invullen a.u.b</h1>";
}
}
?>
<form action="<?php echo $_SERVER["PHP_SELF"]; ?>" method="post" id="form1">
<h1>Vul de gegevens in</h1>
<table>
<tr>
<td>Standnaam:</td>
<td><input type="text" name="standnaam" size="18"/></td>
</tr>
<tr>
<td>Oppervlakte (in m^2):</td>
<td><input type="text" name="oppervlakte" size="6"/></td>
</tr>
<tr>
<td>Verdieping:</td>
<td><input type="checkbox" name="verdieping" value="1"/></td>
<!--value op 1 zetten voor checkbox! indien checked is value 1 -->
</tr>
<tr>
<td>Telefoon:</td>
<td><input type="checkbox" name="telefoon" value="1"/></td>
</tr>
<tr>
<td>Netwerk:</td>
<td><input type="checkbox" name="netwerk" value="1"/></td>
</tr>
<tr>
<td><input type="submit" name="verzenden" value="Verzenden"/></td>
</tr>
</table>
2nd page with calculations:
<?php
$standnaam = $_SESSION["standnaam"];
$oppervlakte = $_SESSION["oppervlakte"];
$verdieping = $_SESSION["verdieping"];
$telefoon = $_SESSION["telefoon"];
$netwerk = $_SESSION["netwerk"];
if ($oppervlakte <= 10)
$tarief = 100;
if ($oppervlakte > 10 && $oppervlakte <= 20)
$tarief = 90;
if ($oppervlakte > 20)
$tarief = 80;
if($verdieping == 1)
{
$prijsVerdieping = $oppervlakte * 120;
}
else
{
$prijsVerdieping = 0;
}
if(($telefoon == 1) && ($netwerk == 1))
{
$prijsCom = 30;
}
if(($telefoon == 1) || ($netwerk == 1))
{
$prijsCom = 20;
}
$prijsOpp = $tarief * $oppervlakte; // werkt
$totalePrijs = $prijsOpp + $prijsVerdieping + $prijsCom;
echo "<table class=\"tableExpo\">";
echo "<th>Standnaam</th>";
echo "<th>Oppervlakte</th>";
echo "<th>Verdieping</th>";
echo "<th>Telefoon</th>";
echo "<th>Netwerk</th>";
echo "<th>Totale prijs</th>";
echo "<tr>";
echo "<td>$standnaam</td>";
echo "<td>$oppervlakte</td>";
echo "<td>$verdieping</td>";
echo "<td>$telefoon</td>";
echo "<td>$netwerk</td>";
echo "<td>$totalePrijs</td>";
echo "</tr>";
echo "</table>";
?>
Terug naar het formulier
</body>
</html>

Answer 1

One problem I've noticed are these lines,
if(($telefoon == 1) && ($netwerk == 1)) {
$prijsCom = 30; // will get set to 30.
}
if(($telefoon == 1) || ($netwerk == 1)) {
$prijsCom = 20; // will now be set to value of 20.
}
Here is why, if $telefoon and $netwerk are both 1, $prijsCom is set to the value of 30. It leaves that if block and goes down onto the next one, i.e.
if(($telefoon == 1) || ($netwerk == 1)) {
$prijsCom = 20;
}
It will evaluate to true since $telefoon == 1 evaluates to true and will override the value of $prijsCom to be 20.
Depending on how the code will be used, as a possible work-around, you could add the || condition first, so the value is set to 20 whether $telefoon or $netwerk is set to 1 and then check to see if they both are 1.
Update:
When looking at your code, I notice you are using $_SESSION variables, but you have not called session_start() at the beginning of the file,
<?php
session_start(); // <--you need to call this first
$standnaam = $_SESSION["standnaam"];
$oppervlakte = $_SESSION["oppervlakte"];
...
This may or may not be where your other problem lies, but whenever you use $_SESSION you need to call session_start first.

Answer 2

Call session_start(); after <?php.