I am a beginner on programming now reading books by Chris P.: 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 M. wrote:
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.
improvement? Thanks.
The fist thing I’d change is to remove all the #to_i’s. You should
convert to integer just once, namely after reading user input. If you
use Integer() for the conversion, then you also get automatic error
checking, i.e., if the user enters “foo” no calculations will be done
but he will see an error message instead.
Next, I am not sure what you are trying to achieve. As far as I can see
there is no condition on the “puts s” but your print statement seems to
indicate that you are interested in leap years only. If you want to
print leap years only then you need to somehow put a condition around
that output statement.
Normally you would need just a single loop as far as I understand the
problem and what you are trying to do. So you could get rid of one of
them.
I would also move the leap year output code inside the if-else. The
code will likely work the way it is as well because if s>e the body of
the while loop will never be executed. But from a control flow point of
view the code becomes clearer when you nest the “activity” (leap year
calculation and output in this case) in the proper branch of the
conditional statement.
puts 'leap year between ' + s + ' and '+ e + ' as below:'
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’
I am a beginner on programming now reading books by Chris P.: 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.
I think it’s easier to use Date#leap? for this question.
puts ‘Starting year:’
start = gets.chop
puts ‘Ending year:’
ending = gets.chop
if start.to_i > ending.to_i
puts ‘Ending year should be bigger than staring year’
else
puts 'Leap year between ’ + start + ’ and ‘+ ending + ’ as below:’
while start.to_i <= ending.to_i
if Date.new(start.to_i).leap?
puts start
end
start = start.to_i + 1
end
end
puts ‘all done’
I am a beginner on programming now reading books by Chris P.: Learn
to Program.
…
while ( (s.to_i % 4 == 0 and s.to_i % 100 != 0) or (s.to_i % 100 ==
0 and s.to_i % 400 == 0 ))
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
Your complex conditional can be expressed more clearly with a series of
if statements:
start = 2000
finish = 2200
year = start
while year <= finish
is_leap =
if year % 400 == 0
true
elsif year % 100 == 0
false
else
year % 4 == 0
end
if is_leap: puts year
end
year += 1
end
Or you can use each() on a Range for your loop, and a case statement
inside the loop:
start = 2000
finish = 2200
user_range = start…finish
user_range.each do |year|
is_leap =
case
when year % 400 == 0
true
when year % 100 == 0
false
else
year % 4 == 0
end
if is_leap: puts year
end
year += 1
Thanks Vic,
I just copy the code and modify it a little,is it mean that I’m
improving?
Right now,I’m reading some ruby book.I want to improve my ruby skill.
I’m a complete programming noob and just starting to learn Ruby. I’m
going through the same book and got stumped on this one.
Now that I see how it’s done, I get everything but the last line (in
Pine’s solution) which is
year = year + 1
What’s the function of this line? I’ve experimented with
changing/eliminating it and I see that it’s necessary, but I still don’t
understand why.
(If it would be best to create a new topic, let me know. Not sure what
the etiquette is here, but I figured it was such a small piece of the
program that I should just add to an existing thread.)
The problem comes from a beginner´s tutorial. Using methods like .leap?
of course work just fine. However, a beginner is not familiar with them.
This a way to do it using the tools showed in the same tutorial up to
that level:
puts “Give me the two years”
year1 = gets.chomp.to_i
year2 = gets.chomp.to_i
puts “This is the list of years:”
if year1 > year2
puts “The second year has to be bigger than the first”
else
while (year1 <= year2)
if
(((year1 % 4 == 0) and (year1 %100 !=0)) or (year1 % 400 == 0))
puts year1.to_s
puts ‘Begin year:’
beginyear = gets.chomp
puts ‘End year:’
endyear = gets.chomp
puts 'The leap years between ’ + beginyear + ’ and ’ + endyear + ‘:’
beginyear = beginyear.to_i
endyear = endyear.to_i
if endyear < beginyear
puts ‘Note: Begin year < End year’
else
while (beginyear <= endyear)
if
(((beginyear % 4 == 0) and (beginyear %100 !=0)) or
(beginyear % 400 == 0))
puts beginyear.to_s
I’m a complete programming noob and just starting to learn Ruby. I’m
going through the same book and got stumped on this one.
Now that I see how it’s done, I get everything but the last line (in
Pine’s solution) which is
year = year + 1
What’s the function of this line? I’ve experimented with
changing/eliminating it and I see that it’s necessary, but I still don’t
understand why.
(If it would be best to create a new topic, let me know. Not sure what
the etiquette is here, but I figured it was such a small piece of the
program that I should just add to an existing thread.)
Feel like kind of a goof now. It just hit me. In case anyone else has
the same mental block - for the program to run through the years one at
a time, it has to be told to do that, which is what the +1 accomplishes.
Seems terribly obvious now.
Hi, I’m also a newbie trying the Leap Year problem using while loops…
Can anyone advice why the following code doesn’t work? Much thanks!
puts “Enter starting year:”
starting_year = gets.chomp.to_i
puts “Enter ending year:”
ending_year = gets.chomp.to_i
while true
year = starting_year
if (year%4==0)&& (year%100!=0)
puts year.to_s + ’ is a Leap Year’
end
year = year +1
break if year >= ending_year
end
Hi, I’m also a newbie trying the Leap Year problem using while loops…
Can anyone advice why the following code doesn’t work? Much thanks!
puts “Enter starting year:”
starting_year = gets.chomp.to_i
puts “Enter ending year:”
ending_year = gets.chomp.to_i
while true
year = starting_year
if (year%4==0)&& (year%100!=0)
puts year.to_s + ’ is a Leap Year’
end
year = year +1
break if year >= ending_year
end
You are resetting the variable “year” to “starting_year” every time to
loop runs. Set the variable “year” outside of the while loop. Also,
there is a leap year every 400 years.
That is what I am talking about… I just ran it from my e-mail…