use Time::Local;

$from_year = $from_year - 1900;
$from_month = $from_month - 1;
$from = timelocal(0,0,0,$from_day,$from_month,$from_year);

$to_year = $to_year - 1900;
$to_month = $to_month - 1;
$to = timelocal(0,0,0,$to_day,$to_month,$to_year);

$days_between = ( ($to - $from) / (60 * 60 * 24) );