View difference between Paste ID: pt53Z4cb and i8prLAUG

 $list = array(
-    1 => array(
+    1 => (object)array(
         'id' => 1,
         'parent' => 0
     ),
-    2 => array(
+    2 => (object)array(
         'id' => 2,
         'parent' => 0
     ),
-    3 => array(
+    3 => (object)array(
         'id' => 3,
         'parent' => 2
     ),
-    4 => array(
+    4 => (object)array(
         'id' => 4,
         'parent' => 2
     ),
-    5 => array(
+    5 => (object)array(
         'id' => 5,
         'parent' => 2
     ),
-    6 => array(
+    6 => (object)array(
         'id' => 6,
         'parent' => 5
     ),
 );
 
-foreach ($list as $id => &$leaf) {
+foreach ($list as $leaf) {
-	if ($leaf['parent'] !== 0) {
+	if ($leaf->parent !== 0) {
-		$list[$id]['children'][] = &$leaf;
+		$list[$leaf->parent]->children[] = $leaf;
         unset($list[$leaf->id]);
 	}
 }
 
 echo "<pre>"; print_r($list); echo "</pre>";