PHP封装函数，获取周日期

//周日期
private function get_week($date)
{
    $date_week  = date("W",strtotime($date));   //上周日期是第几周
    $week_num = date("w",strtotime($date));     //上周日期是星期几

    if($week_num == 0) $week_num = 7;
    $starttime = strtotime($date) - ($week_num-1)*24*3600;  //哪一周开始的时间（因为开始时间直接设置为了周一）
    $endtime = strtotime($date) + (7-$week_num +1)*24*3600 -1; //哪一周结束的时间

    return array(
        'starttime' => $starttime,                          //上周的星期一
        'endtime'   => $endtime,                            //上周的星期日
        'date'      => $date,
        'week_num'  => $week_num,                           //星期几
        'date_week' => date("o",$starttime).'-'.$date_week  //上周是第几周
    );
}