PHP无限分类代码，支持数组格式化、直接输出菜单两种方式

<?php
/**
+------------------------------------------------
* 通用的树型类
+------------------------------------------------
* @author yangyunzhou@foxmail.com
+------------------------------------------------
* @date 2010年11月23日10:09:31
+------------------------------------------------
*/
class Tree
{

/**
+------------------------------------------------
* 生成树型结构所需要的2维数组
+------------------------------------------------
* @author yangyunzhou@foxmail.com
+------------------------------------------------
* @var Array
*/
var $arr = array();

/**
+------------------------------------------------
* 生成树型结构所需修饰符号，可以换成图片
+------------------------------------------------
* @author yangyunzhou@foxmail.com
+------------------------------------------------
* @var Array
*/
var $icon = array('│','├',' └');

/**
* @access private
*/
var $ret = '';

/**
* 构造函数，初始化类
* @param array 2维数组，例如：
* array(
* 1 => array('id'=>'1','parentid'=>0,'name'=>'一级栏目一'),
* 2 => array('id'=>'2','parentid'=>0,'name'=>'一级栏目二'),
* 3 => array('id'=>'3','parentid'=>1,'name'=>'二级栏目一'),
* 4 => array('id'=>'4','parentid'=>1,'name'=>'二级栏目二'),
* 5 => array('id'=>'5','parentid'=>2,'name'=>'二级栏目三'),
* 6 => array('id'=>'6','parentid'=>3,'name'=>'三级栏目一'),
* 7 => array('id'=>'7','parentid'=>3,'name'=>'三级栏目二')
* )
*/
function tree($arr=array())
{
$this->arr = $arr;
$this->ret = '';
return is_array($arr);
}

/**
* 得到父级数组
* @param int
* @return array
*/
function get_parent($myid)
{
$newarr = array();
if(!isset($this->arr[$myid])) return false;
$pid = $this->arr[$myid]['pid'];
$pid = $this->arr[$pid]['pid'];
if(is_array($this->arr))
{
foreach($this->arr as $id => $a)
{
if($a['pid'] == $pid) $newarr[$id] = $a;
}
}
return $newarr;
}

/**
* 得到子级数组
* @param int
* @return array
*/
function get_child($myid)
{
$a = $newarr = array();
if(is_array($this->arr))
{
foreach($this->arr as $id => $a)
{
if($a['pid'] == $myid) $newarr[$id] = $a;
}
}
return $newarr ? $newarr : false;
}

/**
* 得到当前位置数组
* @param int
* @return array
*/
function get_pos($myid,&$newarr)
{
$a = array();
if(!isset($this->arr[$myid])) return false;
$newarr[] = $this->arr[$myid];
$pid = $this->arr[$myid]['pid'];
if(isset($this->arr[$pid]))
{
$this->get_pos($pid,$newarr);
}
if(is_array($newarr))
{
krsort($newarr);
foreach($newarr as $v)
{
$a[$v['id']] = $v;
}
}
return $a;
}

/**
* -------------------------------------
* 得到树型结构
* -------------------------------------
* @author yangyunzhou@foxmail.com
* @param $myid 表示获得这个ID下的所有子级
* @param $str 生成树形结构基本代码, 例如: "<option value=\$id \$select>\$spacer\$name</option>"
* @param $sid 被选中的ID, 比如在做树形下拉框的时候需要用到
* @param $adds
* @param $str_group
*/
function get_tree($myid, $str, $sid = 0, $adds = '', $str_group = '')
{
$number=1;
$child = $this->get_child($myid);
if(is_array($child)) {
$total = count($child);
foreach($child as $id=>$a) {
$j=$k='';
if($number==$total) {
$j .= $this->icon[2];
} else {
$j .= $this->icon[1];
$k = $adds ? $this->icon[0] : '';
}
$spacer = $adds ? $adds.$j : '';
$selected = $id==$sid ? 'selected' : '';
@extract($a);
$parentid == 0 && $str_group ? eval("\$nstr = \"$str_group\";") : eval("\$nstr = \"$str\";");
$this->ret .= $nstr;
$this->get_tree($id, $str, $sid, $adds.$k.'&nbsp;',$str_group);
$number++;
}
}
return $this->ret;
}

/**
* 同上一方法类似,但允许多选
*/
function get_tree_multi($myid, $str, $sid = 0, $adds = '')
{
$number=1;
$child = $this->get_child($myid);
if(is_array($child))
{
$total = count($child);
foreach($child as $id=>$a)
{
$j=$k='';
if($number==$total)
{
$j .= $this->icon[2];
}
else
{
$j .= $this->icon[1];
$k = $adds ? $this->icon[0] : '';
}
$spacer = $adds ? $adds.$j : '';

$selected = $this->have($sid,$id) ? 'selected' : '';
@extract($a);
eval("\$nstr = \"$str\";");
$this->ret .= $nstr;
$this->get_tree_multi($id, $str, $sid, $adds.$k.'&nbsp;');
$number++;
}
}
return $this->ret;
}

function have($list,$item){
return(strpos(',,'.$list.',',','.$item.','));
}

/**
+------------------------------------------------
* 格式化数组
+------------------------------------------------
* @author yangyunzhou@foxmail.com
+------------------------------------------------
*/
function getArray($myid=0, $sid=0, $adds='')
{
$number=1;
$child = $this->get_child($myid);
if(is_array($child)) {
$total = count($child);
foreach($child as $id=>$a) {
$j=$k='';
if($number==$total) {
$j .= $this->icon[2];
} else {
$j .= $this->icon[1];
$k = $adds ? $this->icon[0] : '';
}
$spacer = $adds ? $adds.$j : '';
@extract($a);
$a['title'] = $spacer.' '.$a['title'];
$this->ret[$a['id']] = $a;
$fd = $adds.$k.'&nbsp;';
$this->getArray($id, $sid, $fd);
$number++;
}
}

return $this->ret;
}
}
?>