Problem with session variable named $_SESSION[cart]

[cedtech23]

I create a session variable named $SESSION[cart] to hold the number of items selected in a shopping cart. I then greated a link called <a href=$SERVER[PHP_SELF]?buy=$n>BUY</a> that once selected is suppose to pass the value passed in the buy variable to $SESSION[cart]= $GET[buy]; I thought this would update the number of items in the variable $SESSION[cart] so I created a statement that printed out the results of what is in the cart
$numitems=count($SESSION[cart]);
echo "<td>$numitems Items in Shopping Cart</td> ";

The problem I am having is that every time I selected an Item its not updating the number of items stored in the cart variable.

Can someone tell me what I am doing wrong listed below is the script.

<?php
session_start();
if(!isset($SESSION[cart])){
$SESSION['cart']=array();
}
if(isset($GET[buy])){
$SESSION[cart]= $GET[buy];
header("location: $SERVER[PHP_SELF]");
exit();

}

$products=array('IBM Laptop', 'Dell Laptop', 'Gateway Desktop', 'Service Contract');
$prices=array(200.00, 300.00, 400.00, 199.99);
echo "<table cellspacing=20 >";
echo "<tr><TH>Item Title</th><TH>Price</th></tr>";

for($n=0;$n<count($products);$n++){
echo "<tr>";
echo "<td>$products[$n]</td>";
$price=number_format($prices[$n],2);

echo "<td>$price</td>";
echo "<td><a href=$SERVER[PHP_SELF]?buy=$n>BUY</a></td>";
echo "</tr>";
}
$numitems=count($SESSION[cart]);
echo "<td>$numitems Items in Shopping Cart</td> ";
echo "</table>";

?>

[rachel2004]

In your code, you've created $_SESSION['cart'] (notice the use of the single quotes?) as an array.

In your other check for $GET['buy'], you change the value of $SESSION['cart'] to whatever $GET['buy'] is. I think what were expecting to happen is to add to your array $SESSION['cart']. However, you are merely changing what $SESSION['cart'] is to whatever $GET['buy'] is. Run the code below and you'll see what I mean. Afterwards, visit the PHP manual and look at the section on "arrays" and find yourself the function to add to an array. That should sove your problem:

<?php
$array = array('apple', 'orange', 'banana');

echo "<pre>";
print_r($array);
echo "</pre>";

$array = "some value";

echo "<pre>";
print_r($array);
echo "</pre>";
?>

[cedtech23]

I look on php how to add to an array and found the following info that describes how to use array_push to add to an array in php. they used this example

<?php
$stack = array("orange", "banana");
array_push($stack, "apple", "raspberry");
print_r($stack);
?>

I tried this

if(isset($GET['buy'])){
$SESSION['cart'] = array_push($SESSION['cart'],$GET['buy']);

and got this error

Warning: array_push() [function.array-push]: First argument should be an array in C:\Program Files\Apache Group\Apache2\htdocs\cart2.php on line 7

when every I add a second item.
what is the problem I thought that I declared $_SESSION['cart'] an array?
so what does the error mean???

[rachel2004]

Look at the example you posted from the manual. You'll notice you've done this:

$SESSION['cart'] = array_push($SESSION['cart'],$_GET['buy']);

but if you follow the example, it should be like this:

array_push($SESSION['cart'], $GET['buy']);

[cedtech23]

I got it . Thanks for your help . I learned a lot about arrays and adding to them the right way

[rachel2004]

You're welcome. The PHP manual is well written and has lots of examples. Just scroll through the section what you're working with (such as "arrays" or "file") and more likely than not, someone has already experienced what you're trying to do and there exists a function for it. The user comments also are good examples on how to use the functions if you get stuck.