Question

Can someone please explain to me why I get “Notice: Undefined variable” for variable $subtotal in the 2nd code snippet but NOT in the 1st code snippet ? What’s the difference between them? Are they consider local variables?

Also, exactly what is the variable type (Global, Superglobal.. etc) of $cartKey and $cartItem in the foreach loop? How come I didn’t need to define/declare them?

switch( $_SESSION['shippingMethod'] )
{
  case "Air": 
             $shipping = $subtotal * 0.1;
             break;
}

and

foreach( $cart as $cartKey => $cartItem )
{
    $subtotal += $cartItem['total'];
}

Thank you very much in helping.

Answer 1

Apprently $subtotal doesnt exist yet in the area where the loop is. Since you are using += you are getting this error beacuse you are essentially saying:

$subtotal = $subtotal + $cartItem['total']

in the cases of $cartKey and $cartItem you did define them… they are part of the loop structure you create them from the current key and value of the array item – “copying” them into the current scope from the array. Eg. by doing $cartKey => $cartItem you defined those variables.