$items = array(array('id' => 1, 'pid' => 0, 'name' => '一级11' ),array('id' => 11, 'pid' => 0, 'name' => 'www.111cn.net 一级12' ),array('id' => 2, 'pid' => 1, 'name' => '二级21' ),array('id' => 10, 'pid' => 11, 'name' => '二级22' ),array('id' => 3, 'pid' => 1, 'name' => '二级23' ),array('id' => 12, 'pid' => 11, 'name' => '二级24' ),array('id' => 13, 'pid' => 12, 'name' => '三级31' ),array('id' => 9, 'pid' => 1, 'name' => '二级25' ),);

function formatTree($array, $pid = 0){$arr = array();$tem = array();foreach ($array as $v) {if ($v['pid'] == $pid) {$tem = formatTree($array, $v['id']); //判断是否存在子数组$tem && $v['son'] = $tem;$arr[] = $v;}}return $arr;}