使用数组实现PHP无限级分类

<?php
$cates = array(
 array(
  'cid' => 1,
  'cname' => '新闻',
  'pid' => 0
 ),
 array(
  'cid' => 2,
  'cname' => '通知',
  'pid' => 0
 ),
 array(
  'cid' => 3,
  'cname' => '国内新闻',
  'pid' => 1
 ),
 array(
  'cid' => 4,
  'cname' => '国际新闻',
  'pid' => 1
 ),
 array(
  'cid' => 5,
  'cname' => '北京新闻',
  'pid' => 3
 ),
 array(
  'cid' => 6,
  'cname' => '上海新闻',
  'pid' => 3
 ),
 array(
  'cid' => 7,
  'cname' => '紧急通知',
  'pid' => 2
 ),
 array(
  'cid' => 8,
  'cname' => '一般通知',
  'pid' => 2
 ),
);
/**
 * 生成菜单
 *
 * @param array $data 原始数据
 * @param integer $pid 当前分类的父id
 * @return array 处理后数据
 */
function createMenuTree($data = array(), $pid = 0)
{
 if (empty($data))
 {
  return array();
 }
 static $level = 0;
 $returnArray = array();
 foreach ($data as $node)
 {
  if ($node['pid'] == $pid)
  {
   $returnArray[] = array(
    'cid' => $node['cid'],
    'cname' => $node['cname'],
    'level' => $level
   );
   if (hasChild($node['cid'], $data))
   {
    $level++;
    $returnArray = array_merge($returnArray, createMenuTree($data, $node['cid']));
    $level--;
   }
  }
 }
 return $returnArray;
}
/**
 * 检查是否有子分类
 *
 * @param integer $cid 当前分类的id
 * @param array $data 原始数据
 * @return boolean 是否有子分类
 */
function hasChild($cid, $data)
{
 $hasChild = false;
 foreach ($data as $node)
 {
  if ($node['pid'] == $cid)
  {
   $hasChild = true;
   break;
  }
 }
 return $hasChild;
}
header('Content-Type: text/html; charset=utf-8');
$result = createMenuTree($cates);
foreach ($result as $row)
{
 for ($i = 0; $i < $row['level']; $i++)
 {
  echo "t";
 }
 echo $row['cname'] . "n";
}
?>