php生成无限栏目树

栏目数组:
$arr=Array(

Array('cid' => 2,'cname' => '新闻','pid' => 0),
    Array('cid' => 4,'cname' =>'体育','pid' => 0),
    Array('cid' => 5,'cname' => '娱乐','pid' => 0),
    Array('cid' => 7,'cname' => '热点新闻','pid' =>2),
    Array('cid' => 8,'cname' => '小众新闻','pid' => 2),
    Array('cid' => 9,'cname' => '民谣新闻','pid' => 8),

);

<?php

$arr=Array(

    Array('cid' => 2,'cname' => '新闻','pid' => 0),

    Array('cid' => 4,'cname' =>'体育','pid' => 0),

    Array('cid' => 5,'cname' => '娱乐','pid' => 0),

    Array('cid' => 7,'cname' => '热点新闻','pid' =>2),

    Array('cid' => 8,'cname' => '小众新闻','pid' => 2),

    Array('cid' => 9,'cname' => '民谣新闻','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);

                //判断是否存在子数组

                $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);

?>