$arr=Array(  Array('cid' => 2,'cname' => '新聞','pid' => 0),  Array('cid' => 4,'cname' =>'體育','pid' => 0),  Array('cid' => 5,'cname' => '娛樂','pid' => 0),  Array('cid' => 7,'cname' => '熱點新聞','pid' =>2),  Array('cid' => 8,'cname' => '小眾新聞','pid' => 2),  Array('cid' => 9,'cname' => '民謠新聞','pid' => 8),);

<?php$arr=Array(  Array('cid' => 2,'cname' => '新聞','pid' => 0),  Array('cid' => 4,'cname' =>'體育','pid' => 0),  Array('cid' => 5,'cname' => '娛樂','pid' => 0),  Array('cid' => 7,'cname' => '熱點新聞','pid' =>2),  Array('cid' => 8,'cname' => '小眾新聞','pid' => 2),  Array('cid' => 9,'cname' => '民謠新聞','pid' => 8),);function formatTree($array, $pid = 0,$level = 1,$field = array('pid'=>'pid','id'=>'id','children'=>'children')){    $arr = array();    foreach ($array as &$v) {      if ($v[$field['pid']] == $pid) {        $v['level'] = $level;        $tem = formatTree($array, $v[$field['id']],$v['level']+1,$field);        //判斷是否存在子數組        $tem && $v[$field['children']] = $tem;        $arr[] = $v;      }    }    return $arr;  }$tree = formatTree( $arr,0,1, $field = array('pid'=>'pid','id'=>'cid','children'=>'children') );echo '<pre>';print_r( $tree); ?>