They are ordered by insertion. That's different from for instance objects in Javascript.

Not really

    $arr = array();
    $arr[0] = 'cat';
    $arr[2] = 'dog';
    $arr[1] = 'fish';

    krsort($arr);

    var_dump($arr);

Outputs:

    array(3) 
    {
        [2]=> string(3) "dog" 
        [1]=> string(4) "fish" 
        [0]=> string(3) "cat" 
    }

Well you are explicitly sorting the array by keys, so its not like you are contradicting his sentence. Remove the krsort() call and your "not really" becomes "example".