Online PHP editor | output for JTj7I

<?php function getParentAndChild($data, $id) { $tree = array( "parents" => array(), "children" => array(), "full" => array() ); $current = $data[$id]; $parent_id = $current === NULL ? "NULL" : $current; $child_ids = array($id); $tree['parents'][] = $parent_id; while (isset($data[$parent_id])) { $current = $data[$parent_id]; $parent_id = $current === NULL ? "NULL" : $current; $tree['parents'][] = $parent_id; } while ( count($child_ids) > 0 ) { foreach($child_ids as $child_id) { $children = array_keys($data, $child_id); foreach ($children as $child) $tree['children'][] = $child; $child_ids = $children; } } $tree['full'] = array_merge(array_reverse($tree['parents']), $tree['children']); echo implode(" > ", $tree['full']); } $treeByCat = array( 1 => 0, 2 => 0, 3 => 1, 7 => 1, 4 => 3, 5 => 4, 6 => 5, 8 => 5 ); print_r( getParentAndChild($treeByCat, 4) ); //print_r( getTree($treeByParent, $treeByCat, 4, 0) );