++ed by:

1 PAUSE user

Tatsuhiko Miyagawa


Date::Japanese::Era - Conversion between Japanese Era / Gregorian calendar


  use Date::Japanese::Era;

  # from Gregorian (month + day required)
  $era = Date::Japanese::Era->new(1970, 1, 1);

  # from Japanese Era
  $era = Date::Japanese::Era->new("\x{662D}\x{548C}", 52); # SHOWA

  $name      = $era->name;         # \x{662D}\x{548C} (Unicode flagged)
  $gengou    = $era->gengou;       # Ditto

  $year      = $era->year;         # 52
  $gregorian = $era->gregorian_year;       # 1977

  # use JIS X0301 table for conversion
  use Date::Japanese::Era 'JIS_X0301';

  # more DWIMmy
  use encoding 'utf-8';
  $era = Date::Japanese::Era->new("昭和五十二年");
  $era = Date::Japanese::Era->new("昭和52年");


Date::Japanese::Era handles conversion between Japanese Era and Gregorian calendar.


  $era = Date::Japanese::Era->new($year, $month, $day);
  $era = Date::Japanese::Era->new($era_name, $year);
  $era = Date::Japanese::Era->new($era_year_string);

Constructs new Date::Japanese::Era instance. When constructed from Gregorian date, month and day is required. You need Date::Calc to construct from Gregorian.

Name of era can be either of Japanese / ASCII. If you pass Japanese, the variable should be properly UTF-8 flaged.

Exceptions are thrown when inputs are invalid (e.g: non-existent era name and year combination, unknwon era-name, etc.).

  $name = $era->name;

returns era name in Japanese in Unicode.


alias for name().

  $name_ascii = $era->name_ascii;

returns era name in US-ASCII.

  $year = $era->year;

returns year as Japanese era.

  $year = $era->gregorian_year;

returns year as Gregorian.


  use Date::Japanese::Era;

  # 2001 is H-13
  my $era = Date::Japanese::Era->new(2001, 8, 31);
  printf "%s-%s", uc(substr($era->name_ascii, 0, 1)), $era->year;

  # to Gregorian
  my $era = Date::Japanese::Era->new("\x{5E73}\x{6210}", 13); # HEISEI 13
  print $era->gregorian_year;   # 2001


  • Currently supported era is up to 'meiji'. And before Meiji 05.12.02, gregorius calendar was not used there, but lunar calendar was. This module does not support lunar calendar, but gives warnings in such cases ("In %d they didn't use gregorius calendar").

    To use calendar ealier than that, see DateTime::Calendar::Japanese::Era, which is based on DateTime framework and is more comprehensive.

  • There should be discussion how we handle the exact day the era has changed (former one or latter one?). This module default handles the day as newer one, but you can change so that it sticks to JIS table (older one) by saying:

      use Date::Japanese::Era 'JIS_X0301';

    For example, 1912-07-30 is handled as:

      default       Taishou 1 07-30
      JIS_X0301     Meiji 45 07-30
  • If someday current era (heisei) is changed, Date::Japanese::Era::Table should be upgraded.


Tatsuhiko Miyagawa <miyagawa@bulknews.net>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.


DateTime::Calendar::Japanese::Era, Date::Calc, Encode