From: Josef 'Jupp' Schugt <jupp@...>
Date: 2007-09-02T01:53:43+09:00
Subject: Re: Help with leap year programing

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* HB:

> On chapter 6, I got same assignment. I guess that is a classic one.

So here is a nonclassic solution to this classic problem :)

If s % 4 differs from 0 we start with a year that cannot be a leap year.
If this occurs add 4 - (s % 4) to skip to the next year that is a leap
year unless century rules happen to apply. Now only every fourth year
needs to be considered. A year that can be divided by four is a leap
year under the condition that it can be divided by 400 or cannot be
divided by 100.

puts 'starting year:'
s = gets.chomp.to_i
puts 'ending year:'
e = gets.chomp.to_i

if s > e
    puts 'ending year should be bigger than staring year'
else
    puts "leap year between #{s} and #{e} as below:"
end

s += 4 - (s % 4) if s % 4 != 0

while s  <= e
    puts s if (s % 400 == 0 or s % 100 != 0)
    s += 4
end
puts 'all done'

Josef 'Jupp' Schugt
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Blog available at http://www.mynetcologne.de/~nc-schugtjo/blog/
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