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();