PHP 获取数组任意下标key的上一个prev和下一个next下标值 <?php $xoops[1] = '小';$xoops[2] = '孩';$xoops[3] = '子';$xoops[4] = '气';$steps = new Steps();foreach($xoops as $key=>$value){$steps->add($key);}$steps->setCu