php时间如何转化为星期几

function   get_week($date){
    //强制转换日期格式
    $date_str=date('Y-m-d',strtotime($date));
    //封装成数组
    $arr=explode("-", $date_str);
    //参数赋值
    //年
    $year=$arr[0];
    //月，输出2位整型，不够2位右对齐
    $month=sprintf('%02d',$arr[1]);
    //日，输出2位整型，不够2位右对齐
    $day=sprintf('%02d',$arr[2]);
    //时分秒默认赋值为0；
    $hour = $minute = $second = 0;   
    //转换成时间戳
    $strap = mktime($hour,$minute,$second,$month,$day,$year);
    //获取数字型星期几
    $number_wk=date("w",$strap);
    //自定义星期数组
    $weekArr=array("星期日","星期一","星期二","星期三","星期四","星期五","星期六");
    //获取数字对应的星期
    return $weekArr[$number_wk];
}
 
//测试
/*$date="2016-08-21";
echo get_week($date);
*/
    // echo '<pre>';
foreach ($all as $k => $v) {
    $arr[$k]['time'] = $v['time'];
    $arr[$k]['oprate'] = $v['oprate'];
    $arr[$k]['record'] = $v['record'];
    $arr[$k]['xq'] = get_week($v['time']);
    // var_dump($v);
}