From: Jamis Buck <jgb3@...>
Date: 2003-12-27T07:16:38+09:00
Subject: Re: newbie question on how to subtract two dates.

Tim Hunter wrote:

>On Sat, 27 Dec 2003 06:18:33 +0900, Ruby Ruby wrote:
>
>  
>
>>Is there a ruby method that will allow me to perform something like:
>>today - x and get yesterday?
>>
>>    
>>
>Check out the Date class.
>http://www.ruby-doc.org/stdlib/libdoc/date/rdoc/files/date_rb.html
>
>.
>
>  
>

You just need to subtract (or add) the number of seconds you want from a 
Date to get another date: in other words, to find the date 24 hours 
prior to the current date:

  yesterday = Time.now - 24 * 60 * 60

(Incidentally, I looked at the Date class documentation... I already 
knew how to do Date arithmetic in Ruby and knew what I was looking for, 
and it still took me a while to find where in the documentation it talks 
about how to subtract some value x from a date to get another date.  
Since this is a fairly common operation on dates, could this be given as 
an example somewhere near the front of the docs?  I know I would never 
have found it there if I didn't already know what it was I wanted to do, 
and how to do it.)

-- 
Jamis Buck
jgb3@email.byu.edu

ruby -h | ruby -e 'a=[];readlines.join.scan(/-(.)\[e|Kk(\S*)|le.l(..)e|#!(\S*)/) {|r| a << r.compact.first };puts "\n>#{a.join(%q/ /)}<\n\n"'