Explain - help please

[flyersun]

As part of my assignment I have to explain what all the code I've used does... thats all well and good but I have this code which my tutor wrote and I'm a bit at at loss to work how it works.

This is part of a shoping cart script I know what it does but I'm not to sure how.. can anyone help please?

function showCart() {
global $db;
$cart = $_SESSION['cart'];
if ($cart) {
$items = explode(',',$cart);
$contents = array();
foreach ($items as $item) {
$contents[$item] = (isset($contents[$item])) ? $contents[$item] + 1 : 1;
}

$output[] = '<form action="cart.php?action=update" method="post" id="cart">';
$output[] = '<table>';
foreach ($contents as $id=>$qty) {
$sql = 'SELECT * FROM cds WHERE cdID = '.$id;
$result = $db->query($sql);
$row = $result->fetch();
extract($row);
$output[] = '<tr>';
$output[] = '<td><a href="cart.php?action=delete&id='.$id.'" class="r">Remove</a></td>';
$output[] = '<td>'.$title.' by '.$artist.'</td>';
$output[] = '<td>&pound;'.$price.'</td>';
$output[] = '<td><input type="text" name="qty'.$id.'" value="'.$qty.'" size="3" maxlength="3" /></td>';
$output[] = '<td>&pound;'.($price * $qty).'</td>';
$total += $price * $qty;
$output[] = '</tr>';
}
$output[] = '</table>';
$output[] = '<p>Grand total: <strong>&pound;'.$total.'</strong></p>';
$output[] = '<div><button type="submit">Update cart</button></div>';
$output[] = '</form>';
} else {
$output[] = '<p>You shopping cart is empty.</p>';
}
return join('',$output);

[trq]

Um.... the whole point of the assignment is to see how much [b]you've[/b] learnt, not how much we know.

[flyersun]

ok you have a point.. how about I tell you what I think it means and you tell me if I'm close or not?

[trq]

Sounds fair enough. Go through the code bit by bit and add comments just prior to what you think the code is doing.

[flyersun]

function showCart() {
  //connection to database
  global $db;

  // Get info from the session var and stuff it in $cart
  $cart = $_SESSION['cart'];

  //check if there is anything in $cart
  if ($cart) {

      //If there is something in $cart put it in an array called $items (brake part where there are ,'s)
      $items = explode(',',$cart);

      //create an array called $contents
      $contents = array();

      //Loop, go though the $items array untill there are no more items left
      foreach ($items as $item) {

// This is where I start to get confused it's checking if there is anything in $contents[$item] and
        //then putting what ever's there into putting it back in it's self?  I don't have a clue what the question mark does.
        // but then it seems to be adding 1 to the value and not sure what the last bit does.. hmm
        $contents[$item] = (isset($contents[$item])) ? $contents[$item] + 1 : 1;
      }

[trq]

Ok... that last part actually loops through the array of items, creating a new array of unique keys. For each key it adds up the total and stores it as the value.

Hope that helps... it is actually a little difficult to explain.

[flyersun]

Thanks! that make it alot clearer!

Amy