Description:
------------
The test in the remove_item() function should be
if ($this->items[$artnr] >= $num)
                         ^^

Cheers,
Jan Min?ř

"http://uk2.php.net/manual/en/language.oop5.php":

<?php
class Cart {
   var $items;  // Items in our shopping cart
  
   // Add $num articles of $artnr to the cart
 
   function add_item($artnr, $num) {
       $this->items[$artnr] += $num;
   }
  
   // Take $num articles of $artnr out of the cart
 
   function remove_item($artnr, $num) {
       if ($this->items[$artnr] > $num) {
           $this->items[$artnr] -= $num;
           return true;
       } else {
           return false;
       } 
   }
}
?>