<?php
include('cda.php'); // this simulates database access

function cdStore($cd, $quant, $format="text") { // $format default is "text" if not specified
  global $catalog; // so we have $catalog in this scope
  if ($quant <= $catalog['stock'][$cd]){
    if($format=="json")
       $result="{'Transaction'=>true, quant'=>".$quant.", 'cd'=>".$catalog['name'][$cd].", 'total_price'=>".$quant*$catalog['price'][$cd]."}";
    else
      $result="In Stock - ".$quant." ".$catalog['name'][$cd]."@$".$catalog['price'][$cd]." - Total Price= $" . $quant*$catalog['price'][$cd];
    }
  else {
    if($format=="json")
      $result="{'Transaction'=>false, 'stock'=>".$catalog['stock'][$cd]."}";
    else
      $result="Sorry, Out of Stock.";
  }
  return array('invoice'=>$result);
}

// this fixes problem 3 - we can serve json
// problem 4 - we need another function to create a catalog view

?>