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<?php function datediffInWeeks($date1, $date2) { if($date1 > $date2) return datediffInWeeks($date2, $date1); $first = DateTime::createFromFormat('m/d/Y', $date1); $second = DateTime::createFromFormat('m/d/Y', $date2); return floor($first->diff($second)->days/7); } var_dump(datediffInWeeks('11/1/2013', '11/7/2013'));// 21

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