thinkphp5 数组报 Illegal string offset 'begin'

先看代码在说话 case1 定义的$time['begin']和$time['end']作为取值数组没问题,奇怪的问题出现在case2中,值是正常取到的,但是赋值到$time['begin']和$time['end']出现了报错  Illegal string offset 'begin' ,一番检查无果,只能把这两个值重新定义为数组,($time1 =  strtotime(date("Y-m-d",strtotime("$lastday - 6 days"));$time2  = strtotime($lastday);$time = array(begin =>$time1,end => $time2);)

不知道你们会不会出现这个问题,如果发现我的问题请帮忙指正

switch ($type) {
            case 1: { // 时间类型日
                if(empty($nian) || empty($yue) || empty($ri)){
                    $now = time();
                    $nian = date("Y",$now);
                    $yue =  date("m",$now);
                    $ri =  date("d",$now);
                }
                $time['begin'] = mktime(0,0,0,$yue,$ri,$nian);
                $time['end'] = mktime(23,59,59,($yue+1),$ri,$nian);
            };
                break;
            case 2: { // 按周统计
                if(empty($nian) || empty($yue) || empty($ri)){
                    $now = time();
                    $nian = date("Y",$now);
                    $yue =  date("m",$now);
                    $ri =  date("d",$now);
                }
                $time = $nian."/".$yue."/".$ri;
                $lastday= date("Y-m-d",strtotime("$time Sunday"));

                $time['begin'] =  strtotime(date("Y-m-d",strtotime("$lastday - 6 days")));
                $time['end']  = strtotime($lastday);
//                $time = array(begin =>$time1,end => $time2);
            };
                break;
            default: {
                return '';
            }

        }