本篇文章是对php中二叉树的实现代码进行详细的分析介绍，需要的朋友参考下
二叉树及其变体是数据结构家族里的重要组成部分。最为链表的一种变体，香港空间，网站空间，虚拟主机，二叉树最适合处理需要一特定次序快速组织和检索的数据。
复制代码 代码如下:
data = $d;
}
// traverse the tree, left to right, in pre-order, returning an array
// preorder means that each node's value preceeds its children.
public function traversepreorder() {
// prep some variables.
$l = array();
$r = array();
// read in the left and right children appropriately traversed:
if ($this->left) { $l = $this->left->traversepreorder(); }
if ($this->right) { $r = $this->right->traversepreorder(); }
// return a merged array of the current value, left, and right:
return array_merge(array($this->data), $l, $r);
}
// traverse the tree, left to right, in postorder, returning an array
// postorder means that each node's value follows its children.
public function traversepostorder() {
// prep some variables.
$l = array();
$r = array();
// read in the left and right children appropriately traversed:
if ($this->left) { $l = $this->left->traversepostorder(); }
if ($this->right) { $r = $this->right->traversepostorder(); }
// return a merged array of the current value, left, and right:
return array_merge($l, $r, array($this->data));
}
// traverse the tree, left to right, in-order, returning an array.
// in-order means that values are ordered as left children, then the
// node value, then the right children.
public function traverseinorder() {
// prep some variables.
$l = array();
$r = array();
// read in the left and right children appropriately traversed:
if ($this->left) { $l = $this->left->traverseinorder(); }
if ($this->right) { $r = $this->right->traverseinorder(); }
// return a merged array of the current value, left, and right:
return array_merge($l, array($this->data), $r);
}
}
// let's create a binary tree that will equal the following: 3
/// /
//h 9
/// /
// create the tree:6 a
$tree = new binary_tree_node(3);
$tree->left = new binary_tree_node('h');
$tree->right = new binary_tree_node(9);
$tree->right->left = new binary_tree_node(6);
$tree->right->right = new binary_tree_node('a');
// now traverse this tree in all possible orders and display the results:
// pre-order: 3, h, 9, 6, a
echo '
', implode(', ', $tree->traversepreorder()), '
';
// post-order: h, 9, 6, a, 3
echo '', implode(', ', $tree->traversepostorder()), '
';
// in-order: h, 3, 6, 9, a
echo '', implode(', ', $tree->traverseinorder()), '
';
?>