code to add products to shopping cart

Hi,
I have the following requirement.The user can select a list of items and all the items should get added to the shopping cart at once.For this I am trying out some code.The code I have is as follows```
foreach($idArray as $key => $value) {
echo $idArray[$key]." ";
$_SESSION['cart']->add_cart($idArray[$key]);
}

where idArray is the array of products I have.
The products are getting added,but for some reason the products do not have their prices set and they are all showing 0 as price.
Am I doing something wrong?

If you add those same products to cart from the products page, do they get prices properly?

Are you perhaps trying to add products which have attributes? That will cause problems, because you're not setting attribute data.

Do all the indicated products have a master-categories-id set properly in the database? (usually only a problem if you've linked to many places and then removed links, or imported products and didn't set the master etc)

Hi Dr.Byte,
Thanks for the prompt reply.I will try to clarify further.
If I add the products from the products page they r getting added properly and the prices are getting updated properly.
Yes,I am adding products which have attributes.In my example they are 'Print Finish' and 'Print Size'. So how do I add attributes to the product in php code?
I think the master-categories-id is not a problem as my products are not linked.
Thanks.
-Chaitanya