<?php
function d($arr,$pid,$s) {
  static $r_arr=array();
  static $n = 0;
        $s=$s."&nbsp;&nbsp;&nbsp;";
        for($i=0;$i<count($arr);$i++){
            if($arr[$i]['parentid']==$pid){
                $r_arr[$n]['catname'] = $s.'|-'.$arr[$i]['catname'];
                $r_arr[$n]['catid'] = $arr[$i]['catid'];
    $n++;
                for($j=0;$j<count($arr);$j++){
                    if($arr[$i]['catid']==$arr[$j]['parentid']){
                        $r_arr[$n]['catname'] = $s."&nbsp;&nbsp;&nbsp;|-".$arr[$j]['catname'];
      $r_arr[$n]['catid'] = $arr[$j]['catid'];
      $n++;
                        d($arr,$arr[$j]['catid'],$s."&nbsp;&nbsp;&nbsp;");
                    }
                }
            }


        }
  return $r_arr;
    }
?>

<?php
header("Content-Type:text/html;charset=utf-8");
function d($arr,$pid,$s) {
        $s=$s."&nbsp;&nbsp;&nbsp;";
        for($i=0;$i<count($arr);$i++){
            if($arr[$i][2]==$pid){
                echo $s.$arr[$i][1]."<br>";


                for($j=0;$j<count($arr);$j++){
                    if($arr[$i][0]==$arr[$j][2]){
                        echo $s."&nbsp;&nbsp;&nbsp;".$arr[$j][1]."<br>";
                        d($arr,$arr[$j][0],$s."&nbsp;&nbsp;&nbsp;");
                    }
                }
            }
        }
    }
    $arr1=array('a1','根目录1','0','1');
    $arr2=array('b1','根目录2','0','1');
    $arr3=array('a2','一级目录','a1','2');
    $arr4=array('b2','一级目录','b1','2');
    $arr5=array('a3','二级目录','a2','3');
    $arr6=array('b3','二级目录','b2','3');
    $arr7=array('a4','三级目录','a3','4');
    $arr=array($arr1,$arr2,$arr3,$arr4,$arr5,$arr6,$arr7);
    d($arr,'0'," ");
?>