ceil((strtotime('now')-1483228800)/7/60/60/24)-ceil((Yii::$app->params['term_start_date']-1483228800)/7/60/60/24)+1

以下是测试代码

function prDates($start,$end,$term_start){ // 两个日期之间的所有日期

echo date('Y-m-d',$dt_start).'今天是:'.date('N',$dt_start).'第几周:'.(ceil(($dt_start-strtotime('2017-01-01'))/7/60/60/24)-ceil(($term_start-strtotime('2017-01-01'))/7/60/60/24)+1)."\n";      if(date('N',$dt_start)==7){echo "\n";}	$dt_start = strtotime('+1 day',$dt_start);  }

}

$b=strtotime('2018-09-01'); $a=strtotime('2017-03-13'); prDates('2018-09-01','2019-01-12',$b);