From: Mohit Sindhwani <mo_mail@...>
Date: 2008-02-29T14:35:50+09:00
Subject: Re: Getting number of days in a month

Brian Adkins wrote:
> On Feb 27, 12:07 pm, Morton Goldberg <m_goldb...@ameritech.net> wrote:
>   
>> On Feb 27, 2008, at 11:17 AM, Shandy Nantz wrote:
>>
>>     
>>> This is probably an easy question but I am trying to get at the number
>>> of days that are in a month. I have this calendar that I have
>>> built, the
>>> idea being that when a month turns from February to March, for
>>> example,
>>> the calendar should redisplay itself properly formated showing the new
>>> month and the correct number of days. I have it so that it starts
>>> counting the days on the right day of the week, but I have to know
>>> when
>>> to stop counting. Any ideas, Thanks,
>>>       
>> <code>
>> require "Date"
>> d = Date.new(2008, 2, -1)
>> d.day # => 29
>> </code>
>>
>> You can find the last day of a month by creating a Date object for
>> day -1.
>>
>> Regards, Morton
>>     
>
> And we have a winner :)
>
> I wish I had read your post before posting mine. I need to read the
> stdlib doc more carefully.
>   

This may be a bit of a silly question, but this problem came up for me 
recently and I wasn't able to solve it actually.  I did it another way 
and I'll put the code at the end.

If you look at the documentation for the Time class -  
http://www.ruby-doc.org/core/classes/Time.html
it has the following:

LeapYearMonthDays     =     [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
CommonYearMonthDays     =     [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 
30, 31]

Why can't I access these constants directly?  Perhaps, my Ruby knowledge 
is a bit lacking, but I guessed that if I could access that, I could 
have just used that :-S

Anyway, this is a snippet of what I used eventually for getting the 
number of days in a month.  It's not as short as some of the others, but 
I like it :)

require 'time'
require 'date'

#t is a full date from which we use t.month to find the month for which 
you want the number of days
LeapYearMonthDays      = [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
CommonYearMonthDays = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
if Date.gregorian_leap?(t.year)
   days_of_months = LeapYearMonthDays
else
    days_of_months = CommonYearMonthDays
end

puts "There are #{days_of_months[t.month]} days in this month."

Yes, it's not tested - it's been snipped out of a running application, 
though.

Cheers,
Mohit.
2/29/2008 | 1:35 PM.