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>";