php 无限级分类，超级简单的无限级分类，支持输出树状图

无平台限制
只需要告知id,parentid,name 即可

arr = $arr;
    $this->ret = '';
    return is_array($arr);
  }
 
  
  function get_parent($myid)
  {
    $newarr = array();
    if(!isset($this->arr[$myid])) return false;
    $pid = $this->arr[$myid]['parentid'];
    $pid = $this->arr[$pid]['parentid'];
    if(is_array($this->arr))
    {
      foreach($this->arr as $id => $a)
      {
 if($a['parentid'] == $pid) $newarr[$id] = $a;
      }
    }
    return $newarr;
  }
 
  
  function get_child($myid)
  {
    $a = $newarr = array();
    if(is_array($this->arr))
    {
      foreach($this->arr as $id => $a)
      {
 if($a['parentid'] == $myid) $newarr[$id] = $a;
      }
    }
    return $newarr ? $newarr : false;
  }
 
  
  function get_pos($myid,&$newarr)
  {
    $a = array();
    if(!isset($this->arr[$myid])) return false;
    $newarr[] = $this->arr[$myid];
    $pid = $this->arr[$myid]['parentid'];
    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;
  }
 
  
  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.' ',$str_group);
 $number++;
      }
    }
    return $this->ret;
  }
 
  
  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.' ');
 $number++;
      }
    }
    return $this->ret;
  }
 
  function have($list,$item){
    return(strpos(',,'.$list.',',','.$item.','));
  }
 
  
  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['name'] = $spacer.' '.$a['name'];
 $this->ret[$a['id']] = $a;
 $fd = $adds.$k.' ';
 $this->getArray($id, $sid, $fd);
 $number++;
      }
    }
 
    return $this->ret;
  }
}



$data=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'=>''), 
		 8 => array('id'=>'8','parentid'=>3,'name'=>'三级栏目三'),
		 9 => array('id'=>'9','parentid'=>7,'name'=>'四级分类三'),
     ); 
$tree = new Tree;      
$tree->tree($data);    
 
// 如果使用数组, 请使用 getArray方法 
//$tree->getArray(); 
// 下拉菜单选项使用 get_tree方法 
$html=''; 
$str = "$spacer$name"; 
$html .= $tree->get_tree(0,$str,-1).''; 
echo $html; 
?>