获取指定时间戳的 周一 与 周日

function getWeekday($time){    $time=empty($time)?time():$time;    $benzhou=date('w',$time);//1    $month=date('m',$time);    $day=date('d',$time);    $year=date('Y',$time);    $data['first']=date('Y-m-d',mktime(0,0,0,$month,$day-$benzhou+1,$year));    $data['end']=date('Y-m-d',mktime(0,0,0,$month,$day+7-$benzhou,$year));    return $data;}$time=strtotime('2017-4-20 23:59:59');var_dump(getWeekday($time));