PHP获得本周日期

$date1   =   date("Y-m-d",strtotime("Sunday"));   //周开始   
$date2   =   date("Y-m-d",strtotime("Saturday"));   //周结束
$date1   =   date("Y-m-d",strtotime("last   Sunday"));   //上周开始   
$date2   =   date("Y-m-d",strtotime("last   Saturday"));   //上周结束