Appending data to a session

[Anon]

I've got two questions with sessions.
QUESTION#1
I'm trying to make an application that works something like a shopping cart.
I have a session that stores variables A,B,C in US dollars. Now, another item is selected in Canadian dollars for the same variables in A,B,C.

The problem is, the new A,B,C variables overwrite the first variables A,B,C.
How can I append this data to an existing session.

QUESTION#2
My second question is regarding finding the number of elements in a session.
Let's say that we have in our session
A=1,B=2,C=3,A=2,B=3,C=4
I want to be able to count the number of A's I have AND draw their values at some point in the future.

I hope someone can help me out. Perhaps, should I be using cookies for this instead?
Thanks,
Mike

[Anon]

Welcome to arrays!

Don't make $A, $B, and $C unitary variables, define them as arrays.

<?
$A=$B=$C=Array();
?>

Then, when you want to add a value to the $A array, you simply type:

<?
$A[]=$price;
?>

Want to add everything up? Try this;

<?
$sum=0;
foreach($A as $tmp)
$sum+=$tmp;
?>

How about the # of $A's? Try this:

<?
$count=sizeof($A);
?>

AFAIK, you can have as many array elements as there is memory (real and virtual) on your system to store them.