From: HB <hbqian@...>
Date: 2007-09-01T23:35:04+09:00
Subject: Help with leap year programing

Hi, All,

I am a beginner on programming now reading books by Chris Pine: Learn
to Program.
On chapter 6, I got same assignment. I guess that is a classic one.

I have tried to use what I have learned so far: The loop.

My code is as below. i have run several test without finding any
problem.

Can you help to have a look and throw some light on any possible
improvement? Thanks.

____________________

puts 'starting year:'
s = gets.chop
puts 'ending year:'
e = gets.chop

if s.to_i > e.to_i
  puts 'ending year should be bigger than staring year'
  else
    puts 'leap year between ' + s + ' and '+ e + ' as below:'
end

while s.to_i  < e.to_i

  while ( (s.to_i % 4 == 0 and s.to_i % 100 != 0) or (s.to_i % 100 ==
0 and s.to_i % 400 == 0 ))
      puts s
      s = s.to_i + 1
      end
s = s.to_i + 1
end
puts 'all done'


On Nov 7, 2006, at 12:15 PM, Shiloh Madsen wrote:


> So, I'm trying to go through the Teach Yourself Programming book by
> Pragmatic Press and I am encountering a few hurdles. The chapter I am
> working on now is asking me to create a program which will ask for a
> start and end year and then calculate all leap years in that range.
> The logic behind leap years (for those who need a refresher) is all
> years divisible by for are leap years EXCEPT those that are divisible
> by 100 UNLESS they are also divisible by 400. I am somewhat at a loss
> for how to handle the logic for this...finding all numbers that are
> divisible by 4 and removing those divisible by 100 is easy. Its adding
> in that third condition which adds some of the removed numbers back
> into the "true" group that I am having trouble with...or maybe I am
> just not wrapping my mind around the problem well
> enough...suggestions?


The key point of all the methods proposed in this thread is: deal
with the years divisible by 400 first, the years divisible by 100
second, and the years divisible by 4 last of all.

Regards, Morton