| Author |
Time (leap year??)
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| csjasnoch@wisc.edu 2005-08-31, 7:00 pm |
| Is there a simple way to see if a year is a leap year (rather than
writting an algorithm I wanted to check if it is already implimented
first)
It would be kewl if there was just a check on a Time var
Like,
now = Time.new
flag = now.leapyear?
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| csjasnoch@wisc.edu 2005-08-31, 7:00 pm |
| I know I could do somethine like this (and it works for future years)
now = Time.new
leap = now.year%4
if(learp == 0)
flag = true
#############
But if I were to use mktime and involved past dates I would have to be
weary of the millenias.
How does it work
Every 4 years, every hundred but not every millenia.. Or is it also not
every 100?
FYI I am trying to make a w day hash generator. So I send the year
and month and get all wdays for every day of the month.
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| David A. Black 2005-08-31, 7:00 pm |
| Hi --
On Thu, 1 Sep 2005, csjasnoch@wisc.edu wrote:
> Is there a simple way to see if a year is a leap year (rather than
> writting an algorithm I wanted to check if it is already implimented
> first)
>
> It would be kewl if there was just a check on a Time var
>
>
> Like,
>
> now = Time.new
> flag = now.leapyear?
Yes:
irb(main):023:0> Date.today.leap?
=> false
irb(main):024:0> (Date.today << 12).leap?
=> true
David
--
David A. Black
dblack@wobblini.net
| |
| Michael Kelly 2005-08-31, 7:00 pm |
| Try:
now =3D DateTime.now
flag =3D Date.leap?( now.year )
--=20
Michael Kelly=20
Sr. Software Engineer=20
Eleven Wireless Inc. - The Possibilities are Wireless=20
http://www.elevenwireless.com=20
-----Original Message-----
From: csjasnoch@wisc.edu [mailto:csjasnoch@wisc.edu]=20
Sent: Wednesday, August 31, 2005 1:06 PM
To: ruby-talk ML
Subject: Time (leap year??)
Is there a simple way to see if a year is a leap year (rather than
writting an algorithm I wanted to check if it is already implimented
first)
It would be kewl if there was just a check on a Time var
Like,
now =3D Time.new
flag =3D now.leapyear?
| |
| csjasnoch@wisc.edu 2005-08-31, 7:00 pm |
| Wow that was fast:)
Thanx
| |
| Kirk Haines 2005-08-31, 7:00 pm |
| On Wednesday 31 August 2005 2:06 pm, csjasnoch@wisc.edu wrote:
> Is there a simple way to see if a year is a leap year (rather than
> writting an algorithm I wanted to check if it is already implimented
> first)
>
> It would be kewl if there was just a check on a Time var
irb(main):001:0> require 'date'
=> true
irb(main):002:0> d = Date.parse(Time.now.to_s)
=> #<Date: 4907227/2,0,2299161>
irb(main):003:0> d.to_s
=> "2005-08-31"
irb(main):004:0> d.leap?
=> false
Kirk Haines
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| csjasnoch@wisc.edu 2005-08-31, 7:00 pm |
| Where could I find descriptions of the DateTime class?
I only really know about the Time class....
Does it have all of the same members and methods?
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| csjasnoch@wisc.edu 2005-08-31, 7:00 pm |
| Thanks Kirk. That should get me to where I need.
| |
| Michael Kelly 2005-08-31, 7:00 pm |
| I usually go here: http://www.ruby-doc.org/stdlib/.
Look in the Date package.
-=3Dmichael=3D-
--=20
Michael Kelly=20
Sr. Software Engineer=20
Eleven Wireless Inc. - The Possibilities are Wireless=20
http://www.elevenwireless.com=20
-----Original Message-----
From: csjasnoch@wisc.edu [mailto:csjasnoch@wisc.edu]=20
Sent: Wednesday, August 31, 2005 1:21 PM
To: ruby-talk ML
Subject: Re: Time (leap year??)
Where could I find descriptions of the DateTime class?
I only really know about the Time class....
Does it have all of the same members and methods?
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| Kirk Haines 2005-08-31, 7:00 pm |
| On Wednesday 31 August 2005 2:26 pm, csjasnoch@wisc.edu wrote:
> Thanks Kirk. That should get me to where I need.
As you saw, there are more concise ways to do a check for today, but that
general pattern will work for any date that you need to parse. If you are
going from Time to Date a lot, you might want to define something like this:
class Time
def to_date
Date.new(year,month,day)
end
end
Take a look at the difference between Date/DateTime and Time classes. They
are very different. Date/time is stored in a completely different format,
and for the most part they offer completely different sets of methods.
Kirk Haines
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| Gavin Kistner 2005-08-31, 9:56 pm |
| On Aug 31, 2005, at 2:11 PM, csjasnoch@wisc.edu wrote:
> How does it work
> Every 4 years, every hundred but not every millenia.. Or is it also
> not
> every 100?
"Every year divisible by 4 is a leap year.
But every year divisible by 100 is NOT a leap year
Unless the year is also divisible by 400, then it is still a leap year."
-- http://www.timeanddate.com/date/leapyear.html
So to calculate it on your own:
irb(main):001:0> def is_leap?( year ); year % 4 == 0 && ( year % 100 !
= 0 || year % 400 == 0 ); end
=> nil
irb(main):002:0> is_leap? 1996
=> true
irb(main):003:0> is_leap? 1997
=> false
irb(main):004:0> is_leap? 2000
=> true
irb(main):005:0> is_leap? 2100
=> false
irb(main):006:0> is_leap? 2300
=> false
irb(main):007:0> is_leap? 2400
=> true
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