官方网址：http://search.cpan.org/~stbey/Date-Calc-6.3/lib/Date/Calc.pod#___top

  use Date::Calc qw(
      Days_in_Year
      Days_in_Month
      Weeks_in_Year
      leap_year
      check_date
      check_time
      check_business_date
      Day_of_Year
      Date_to_Days
      Day_of_Week
      Week_Number
      Week_of_Year
      Monday_of_Week
      Nth_Weekday_of_Month_Year
      Standard_to_Business
      Business_to_Standard
      Delta_Days
      Delta_DHMS
      Delta_YMD
      Delta_YMDHMS
      N_Delta_YMD
      N_Delta_YMDHMS
      Normalize_DHMS
      Add_Delta_Days
      Add_Delta_DHMS
      Add_Delta_YM
      Add_Delta_YMD
      Add_Delta_YMDHMS
      Add_N_Delta_YMD
      Add_N_Delta_YMDHMS
      System_Clock
      Today
      Now
      Today_and_Now
      This_Year
      Gmtime
      Localtime
      Mktime
      Timezone
      Date_to_Time
      Time_to_Date
      Easter_Sunday
      Decode_Month
      Decode_Day_of_Week
      Decode_Language
      Decode_Date_EU
      Decode_Date_US
      Fixed_Window
      Moving_Window
      Compress
      Uncompress
      check_compressed
      Compressed_to_Text
      Date_to_Text
      Date_to_Text_Long
      English_Ordinal
      Calendar
      Month_to_Text
      Day_of_Week_to_Text
      Day_of_Week_Abbreviation
      Language_to_Text
      Language
      Languages
      Decode_Date_EU2
      Decode_Date_US2
      Parse_Date
      ISO_LC
      ISO_UC
  );

  use Date::Calc qw(:all);

  Days_in_Year
      $days = Days_in_Year($year,$month);

  Days_in_Month
      $days = Days_in_Month($year,$month);

  Weeks_in_Year
      $weeks = Weeks_in_Year($year);

  leap_year
      if (leap_year($year))

  check_date
      if (check_date($year,$month,$day))

  check_time
      if (check_time($hour,$min,$sec))

  check_business_date
      if (check_business_date($year,$week,$dow))

  Day_of_Year
      $doy = Day_of_Year($year,$month,$day);

  Date_to_Days
      $days = Date_to_Days($year,$month,$day);

  Day_of_Week
      $dow = Day_of_Week($year,$month,$day);

  Week_Number
      $week = Week_Number($year,$month,$day);          # DEPRECATED

  Week_of_Year
      ($week,$year) = Week_of_Year($year,$month,$day); # RECOMMENDED
      $week = Week_of_Year($year,$month,$day);         # DANGEROUS

  Monday_of_Week
      ($year,$month,$day) = Monday_of_Week($week,$year);

  Nth_Weekday_of_Month_Year
      if (($year,$month,$day) =
      Nth_Weekday_of_Month_Year($year,$month,$dow,$n))

  Standard_to_Business
      ($year,$week,$dow) =
      Standard_to_Business($year,$month,$day);

  Business_to_Standard
      ($year,$month,$day) =
      Business_to_Standard($year,$week,$dow);

  Delta_Days
      $Dd = Delta_Days($year1,$month1,$day1,
                       $year2,$month2,$day2);

  Delta_DHMS
      ($Dd,$Dh,$Dm,$Ds) =
      Delta_DHMS($year1,$month1,$day1, $hour1,$min1,$sec1,
                 $year2,$month2,$day2, $hour2,$min2,$sec2);

  Delta_YMD
      ($Dy,$Dm,$Dd) =
      Delta_YMD($year1,$month1,$day1,
                $year2,$month2,$day2);

  Delta_YMDHMS
      ($D_y,$D_m,$D_d, $Dh,$Dm,$Ds) =
      Delta_YMDHMS($year1,$month1,$day1, $hour1,$min1,$sec1,
                   $year2,$month2,$day2, $hour2,$min2,$sec2);

  N_Delta_YMD
      ($Dy,$Dm,$Dd) =
      N_Delta_YMD($year1,$month1,$day1,
                  $year2,$month2,$day2);

  N_Delta_YMDHMS
      ($D_y,$D_m,$D_d, $Dhh,$Dmm,$Dss) =
      N_Delta_YMDHMS($year1,$month1,$day1, $hour1,$min1,$sec1,
                     $year2,$month2,$day2, $hour2,$min2,$sec2);

  Normalize_DHMS
      ($Dd,$Dh,$Dm,$Ds) =
      Normalize_DHMS($Dd,$Dh,$Dm,$Ds);

  Add_Delta_Days
      ($year,$month,$day) =
      Add_Delta_Days($year,$month,$day,
                     $Dd);

  Add_Delta_DHMS
      ($year,$month,$day, $hour,$min,$sec) =
      Add_Delta_DHMS($year,$month,$day, $hour,$min,$sec,
                     $Dd,$Dh,$Dm,$Ds);

  Add_Delta_YM
      ($year,$month,$day) =
      Add_Delta_YM($year,$month,$day,
                   $Dy,$Dm);

  Add_Delta_YMD
      ($year,$month,$day) =
      Add_Delta_YMD($year,$month,$day,
                    $Dy,$Dm,$Dd);

  Add_Delta_YMDHMS
      ($year,$month,$day, $hour,$min,$sec) =
      Add_Delta_YMDHMS($year,$month,$day, $hour,$min,$sec,
                       $D_y,$D_m,$D_d, $Dh,$Dm,$Ds);

  Add_N_Delta_YMD
      ($year,$month,$day) =
      Add_N_Delta_YMD($year,$month,$day,
                      $Dy,$Dm,$Dd);

  Add_N_Delta_YMDHMS
      ($year,$month,$day, $hour,$min,$sec) =
      Add_N_Delta_YMDHMS($year,$month,$day, $hour,$min,$sec,
                         $D_y,$D_m,$D_d, $Dhh,$Dmm,$Dss);

  System_Clock
      ($year,$month,$day, $hour,$min,$sec, $doy,$dow,$dst) =
      System_Clock([$gmt]);

  Today
      ($year,$month,$day) = Today([$gmt]);

  Now
      ($hour,$min,$sec) = Now([$gmt]);

  Today_and_Now
      ($year,$month,$day, $hour,$min,$sec) = Today_and_Now([$gmt]);

  This_Year
      $year = This_Year([$gmt]);

  Gmtime
      ($year,$month,$day, $hour,$min,$sec, $doy,$dow,$dst) =
      Gmtime([time]);

  Localtime
      ($year,$month,$day, $hour,$min,$sec, $doy,$dow,$dst) =
      Localtime([time]);

  Mktime
      $time = Mktime($year,$month,$day, $hour,$min,$sec);

  Timezone
      ($D_y,$D_m,$D_d, $Dh,$Dm,$Ds, $dst) = Timezone([time]);

  Date_to_Time
      $time = Date_to_Time($year,$month,$day, $hour,$min,$sec);

  Time_to_Date
      ($year,$month,$day, $hour,$min,$sec) = Time_to_Date([time]);

  Easter_Sunday
      ($year,$month,$day) = Easter_Sunday($year);

  Decode_Month
      if ($month = Decode_Month($string[,$lang]))

  Decode_Day_of_Week
      if ($dow = Decode_Day_of_Week($string[,$lang]))

  Decode_Language
      if ($lang = Decode_Language($string))

  Decode_Date_EU
      if (($year,$month,$day) = Decode_Date_EU($string[,$lang]))

  Decode_Date_US
      if (($year,$month,$day) = Decode_Date_US($string[,$lang]))

  Fixed_Window
      $year = Fixed_Window($yy);

  Moving_Window
      $year = Moving_Window($yy);

  Compress
      $date = Compress($year,$month,$day);

  Uncompress
      if (($century,$year,$month,$day) = Uncompress($date))

  check_compressed
      if (check_compressed($date))

  Compressed_to_Text
      $string = Compressed_to_Text($date[,$lang]);

  Date_to_Text
      $string = Date_to_Text($year,$month,$day[,$lang]);

  Date_to_Text_Long
      $string = Date_to_Text_Long($year,$month,$day[,$lang]);

  English_Ordinal
      $string = English_Ordinal($number);

  Calendar
      $string = Calendar($year,$month[,$orthodox[,$lang]]);

  Month_to_Text
      $string = Month_to_Text($month[,$lang]);

  Day_of_Week_to_Text
      $string = Day_of_Week_to_Text($dow[,$lang]);

  Day_of_Week_Abbreviation
      $string = Day_of_Week_Abbreviation($dow[,$lang]);

  Language_to_Text
      $string = Language_to_Text($lang);

  Language
      $lang = Language();
      Language($lang);               # DEPRECATED
      $oldlang = Language($newlang); # DEPRECATED

  Languages
      $max_lang = Languages();

  Decode_Date_EU2
      if (($year,$month,$day) = Decode_Date_EU2($string[,$lang]))

  Decode_Date_US2
      if (($year,$month,$day) = Decode_Date_US2($string[,$lang]))

  Parse_Date
      if (($year,$month,$day) = Parse_Date($string[,$lang]))

  ISO_LC
      $lower = ISO_LC($string);

  ISO_UC
      $upper = ISO_UC($string);

  Version
      $string = Date::Calc::Version();