question2.php

$regions = array();
$regions[65] = array('id' => 65, 'parent_id' => 44, 'name' => "Shoreditch");
$regions[77] = array('id' => 77, 'parent_id' => 5, 'name' => "England");
$regions[100] = array('id' => 100, 'parent_id' => 0, 'name' => "Europe");
$regions[5] = array('id' => 5, 'parent_id' => 100, 'name' => "United Kingdom");
$regions[44] = array('id' => 44, 'parent_id' => 77, 'name' => "London");


function getChild ($parent_id = 0)
{
  global $regions;
    $value = '';
    foreach ($regions as $location)
    {
      if ($location['parent_id'] == 0)
      {
          echo $location['name'].', ';
          getChild($locatoin['id']); // print child
      }
    }
}

getChild(0); // start with parent_id 0;

// this should print — Europe, United Kingdom, England, London, Shoreditch