Author image Dave Cross
and 1 contributors


Calendar::Simple - Perl extension to create simple calendars


  use Calendar::Simple;

  my @curr      = calendar;             # get current month
  my @this_sept = calendar(9);          # get 9th month of current year
  my @sept_2002 = calendar(9, 2002);    # get 9th month of 2002
  my @monday    = calendar(9, 2002, 1); # get 9th month of 2002,
                                        # weeks start on Monday

  my @span      = date_span(mon   => 10,  # returns span of dates
                            year  => 2006,
                            begin => 15,
                            end   => 28);


A very simple module that exports one function called calendar.


This function returns a data structure representing the dates in a month. The data structure returned is an array of array references. The first level array represents the weeks in the month. The second level array contains the actual days. By default, each week starts on a Sunday and the value in the array is the date of that day. Any days at the beginning of the first week or the end of the last week that are from the previous or next month have the value undef.

If the month or year parameters are omitted then the current month or year are assumed.

A third, optional parameter, start_day, allows you to set the day each week starts with, with the same values as localtime sets for wday (namely, 0 for Sunday, 1 for Monday and so on).


This function returns a cut-down version of a month data structure which begins and ends on dates other than the first and last dates of the month. Any weeks that fall completely outside of the date range are removed from the structure and any days within the remaining weeks that fall outside of the date range are set to undef.

As there are a number of parameters to this function, they are passed using a named parameter interface. The parameters are as follows:


The required year. Defaults to the current year if omitted.


The required month. Defaults to the current month if omitted.


The first day of the required span. Defaults to the first if omitted.


The last day of the required span. Defaults to the last day of the month if omitted.


Indicates the day of the week that each week starts with. This takes the same values as the optional third parameter to calendar. The default is 1 (for Monday).

NOTE: As of version 2.0.0, the default start_day has changed. Previously, it was Sunday; now, it is Monday. This is so the default behaviour matches that of the standard Unix cal command.

This function isn't exported by default, so in order to use it in your program you need to use the module like this:

  use Calendar::Simple 'date_span';


A simple cal replacement would therefore look like this:


  use strict;
  use warnings;
  use Calendar::Simple;

  my @months = qw(January February March April May June July August
                  September October November December);

  my $mon = shift || (localtime)[4] + 1;
  my $yr  = shift || (localtime)[5] + 1900;

  my @month = calendar($mon, $yr);

  print "\n$months[$mon -1] $yr\n\n";
  print "Su Mo Tu We Th Fr Sa\n";
  foreach (@month) {
    print map { $_ ? sprintf "%2d ", $_ : '   ' } @$_;
    print "\n";

A version of this example, called pcal, is installed when you install this module.

Date Range

This module will make use of DateTime if it is installed. By using DateTime it can use any date that DateTime can represent. If DateTime is not installed it uses Perl's built-in date handling and therefore can't deal with dates before 1970 and it will also have problems with dates after 2038 on a 32-bit machine.




Dave Cross <>


With thanks to Paul Mison <> for the start day patch.


Copyright (C) 2002-2008, Magnum Solutions Ltd. All Rights Reserved.


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


perl, localtime, DateTime