31
 32     while(!empty($stack)) {
 33         $cnode = array_pop($stack);
 34         $traverse_data[]=$cnode->data;
 35         if ($cnode->right != null) array_push($stack, $cnode->right);
 36         if ($cnode->left != null) array_push($stack, $cnode->left);
 37     }
 38     return $traverse_data;
 39 }
 40
 41 $root = new Node();
 42 $node1 = new Node();
 43 $node2 = new Node();
 44 $node3 = new Node();
 45 $node4 = new Node();
 46 $node5 = new Node();
 47 $node6 = new Node();
 48 $node7 = new Node();
 49 $node8 = new Node();
 50
 51 $root->data = 1;
 52 $node1->data = 2;
 53 $node2->data = 3;
 54 $node3->data = 4;
 55 $node4->data = 5;
 56 $node5->data = 6;
 57 $node6->data = 7;
 58 $node7->data = 8;
 59 $node8->data = 9;
 60

 61 $root->left = $node1;
 62 $root->right = $node2;
 63 $node1->left = $node3;
 64 $node1->right = $node4;
 65 $node2->left = $node5;
 66 $node2->right = $node6;
 67 $node5->left = $node7;
 68 $node5->right = $node8;
 69
 70 $res = b_first($root);
 71 var_dump($res);
 72 $res1 = depth_first($root);
 73 var_dump($res1);
 74 echo "<br>";