Unable to modify array element value

Question

I have some code that loops through an array, and, if an element of it has a qty of more than 1, copies that element out into as many elements as the qty and then sets the qty of all of them to 1 (and makes a few other changes.)

I've been staring at this for a long time, and I'm sure I must be missing something obvious, because I cannot for the life of me get it to change the values I want to change.

Here's the basic code:

foreach ($items as $id => $itm) {
    // if there's an item that has a qty > 1, need to split out into multiple nodes with qty = 1
    if ($itm['qty'] > 1) {
        $qtyCount = $itm['qty'];
        $newItems = array_fill($id, $qtyCount, $itm);

        foreach ($newItems as $newId => $n) {
            $n['qty'] = 1;
            $n['deal_id'] = $newId;
        }

        error_log("new items");
        error_log(print_r($newItems,1));
    }
}

What I would start with is an array that looks like this:

[items] => Array
    (
        [0] => Array
            (
                [product] => AW8B
                [qty] => 1
                [subtotal] => 6.500
                [deal_id] => 
            )

        [1] => Array
            (
                [product] => C
                [qty] => 3
                [subtotal] => 30.000
                [deal_id] => 1
            )

        [2] => Array
            (
                [product] => QUEPAP
                [qty] => 1
                [subtotal] => 4.000
                [deal_id] => 
            )

    )

In this case, only element 1 in the original items array meets the criteria of qty > 1, so the code should create a new array containing three identical elements to start with. Then the foreach($newItems as $newId => $n) loop should loop through the new, 3-element array, and set the qty element for each one to 1 and the deal_id element to the loop index. What I would expect the error_log(print_r($newItems,1)) line to return is something that looks like the following.

[newItems] => Array
(
    [1] => Array 
        (
            [product] => C
            [qty] => 1
            [subtotal] => 30.000
            [deal_id] => 1
        )

    [2] => Array
        (
            [product] => C
            [qty] => 1
            [subtotal] => 30.000
            [deal_id] => 2
        )

    [3] => Array
        (
            [product] => C
            [qty] => 1
            [subtotal] => 30.000
            [deal_id] => 3
        )
) 

However, the qty remains 3 and the deal_id remains 1 for all of them, even after the internal foreach loop has run. This is driving me up a wall, because I'm not a newbie and have done this kind of thing before. Just cannot for the life of me figure out what I'm doing wrong here.

Answer 1

I would do it as Leonardo shows, but an alternate:

foreach ($newItems as $newId => $n) {
    $newItems[$newId]['qty'] = 1;
    $newItems[$newId]['deal_id'] = $newId;
}

Answer 2

To modify an array directly in a foreach loop you must use '&', like this:

foreach ($newItems as $newId => &$n) {
    ....
}

See the docs