1)  How do I compare two dates?

    Solution #1:

      use Date::Calc qw( Date_to_Days );

      if (Date_to_Days($year1,$month1,$day1)  <
          Date_to_Days($year2,$month2,$day2))

      if (Date_to_Days($year1,$month1,$day1)  <=
          Date_to_Days($year2,$month2,$day2))

      if (Date_to_Days($year1,$month1,$day1)  >
          Date_to_Days($year2,$month2,$day2))

      if (Date_to_Days($year1,$month1,$day1)  >=
          Date_to_Days($year2,$month2,$day2))

      if (Date_to_Days($year1,$month1,$day1)  ==
          Date_to_Days($year2,$month2,$day2))

      if (Date_to_Days($year1,$month1,$day1)  !=
          Date_to_Days($year2,$month2,$day2))

      $cmp = (Date_to_Days($year1,$month1,$day1)  <=>
              Date_to_Days($year2,$month2,$day2));

    Solution #2:

      use Date::Calc qw( Delta_Days );

      if (Delta_Days($year1,$month1,$day1,
                     $year2,$month2,$day2) > 0)

      if (Delta_Days($year1,$month1,$day1,
                     $year2,$month2,$day2) >= 0)

      if (Delta_Days($year1,$month1,$day1,
                     $year2,$month2,$day2) < 0)

      if (Delta_Days($year1,$month1,$day1,
                     $year2,$month2,$day2) <= 0)

      if (Delta_Days($year1,$month1,$day1,
                     $year2,$month2,$day2) == 0)

      if (Delta_Days($year1,$month1,$day1,
                     $year2,$month2,$day2) != 0)