From: jgheal@...
Date: 2008-11-26T06:20:26+09:00
Subject: Re: Chris Pine tutorial assistance chapter 7 sort data without use of 	.sort method

On Nov 25, 2:37 pm, Hugh Sasse <h...@dmu.ac.uk> wrote:
> On Tue, 25 Nov 2008, jgh...@googlemail.com wrote:
> > I'm learning to progam and came accross Chris Pine's Ruby Tutorial.
>
> > I've got to the Array and Iterators chapter (http://pine.fm/LearnToProgram/?Chapter=07
> > ).
>
> > and the following assignment " Let's write a program which asks us to
> > type in as many words as we want (one word per line, continuing until
> > we just press Enter on an empty line), and which then repeats the
> > words back to us in alphabetical order. OK? "
>
> That's all fairly clear....
>
>
>
> > ****** HOWEVER I'm not allowed to use the .sort method ********
>
> That's also clear, you are writing a sort program to teach you about
> programming, rather than to teach you to explore the library.
>
>
>
> > The covered chapters (1 ~ 7) have not covered method creation,
> > Classes, Blocks or Procs, so the challenge is to solve the assignment
> > without using them ( which is dandy since I don't know what they are
> > and I want to solve this assignment before I move forward to discover
> > what they are).
>
> OK
>
>
>
> > This is what I've come up with so far, however when run.... It's not
> > working - surprise surprise.
>
> > Could someone initially give me an idea of what is going wrong rather
> > than rectify my code.
>
> This is rather difficult.  Why?
>
> You have told us what the outcome of the program should be.
> You have shown us a program that doesn't work.
>
> There could be several things wrong, including the mental model you
> have built.  It would be a big help to us in helping you if you told
> us how you intended the program to work.  It may be that you have
> misunderstood something, so expressed your idea poorly in code. Which
> is OK of course, that's the point of learning.  It may be that the
> algorithm you have chosen to implement doesn't work, so even if the
> program implements it correctly, you won't get the answer you want..
>
> So the next thing to learn about programming is that comments are to
> express intention, to give people a bird's eye view of the code so they
> can see what the programmer was trying to do, when that is not immediately
> obvious from the code, or when the code could be wrong, expressing another
> idea.
>
> Add comments to this to explain your intentions about each major section
> and then we can tell you if your code expresses that intention
>
>
>
>
>
> > puts 'Type in as many words as you want and once you\'ve had enough,
> > just \'enter\' a clear line.'
>
> > words_array = []
>
> > loop do
> >    input = gets.downcase.chomp
> >    break if input.empty?
> >    words_array << input
>
> > end
>
> > wordCheck = words_array.last
> > rotateCounter = 0
> > sortedWords_array = []
> > until words_array.length == 0
> >    while rotateCounter <= words_array.length
> >            if words_array[0] >= wordCheck
>
> >                    words_array.push words_array.shift
> >                    rotateCounter = rotateCounter + 1
>
> >            else wordCheck = words_array[0]
> >                    rotateCounter = 0
> >            end
>
> >    end
> >    sortedWords_array.push wordCheck
>
> >    until wordCheck = words_array.last
> >            words_array.push words_array.shift
> >    end
> >    words_array.pop
> >    rotateCounter = 0
> >    wordCheck = words_array.last
> > end
> > puts sortedWords_array
>
> > # Any help greatly appreciated
>
>         Hugh

# basic mental model - store words in 1st array (words_array). Find
the 'smallest' word alphabetically by selecting the last word (call it
wordCheck) from words_array and compare wordCheck with the first word,
second word and so on..... and exchange the value of wordCheck with
the other word (1st/2nd... word) if the other word value happens to be
less. Start the checking again with the first word, second word....
and so on until a counter has been reached (counter equal to 'current'
length of words_array). Once the counter has been reached, put the
value of wordCheck into a second array (sortedWords_array) and delete
wordCheck value from first unsorted array (words_array) and repeat
until words_array is empty.


puts 'Type in as many words as you want and once you\'ve had enough,
just \'enter\' a clear line.'

words_array = []	# create 1st array called words_array to store users
unsorted values

loop do
   input = gets.downcase.chomp	# take the user input, remove the
'enter' off the tail and lower the case and call ...
   break if input.empty?	# .. it 'input' , break from the loop if
'input' is equal to empty
   words_array << input		# push 'input' to the words_array

end

wordCheck = words_array.last	# wordCheck is equal to the last 'input'
stored in the words_array
rotateCounter = 0
sortedWords_array = [] 		# create 2nd array to contain 'sorted' values

until words_array.length == 0	# exit once no words left in the first
unsorted array

	while rotateCounter <= words_array.length # exit if rotate counter
greater than words contained within first array
		if words_array[0] >= wordCheck # continue if first word in 1st array
greater or equal to wordCheck value

			words_array.push words_array.shift # rotate the first unsorted
array
			rotateCounter = rotateCounter + 1 # add 1 to counter

		else wordCheck = words_array[0] # replace current value (wordCheck)
with 'smaller' word
			rotateCounter = 0	# reset counter to zero
		end

	end

	sortedWords_array.push wordCheck	# add wordCheck value to 2nd array

	until wordCheck = words_array.last	# rotate first array until a
matching ..
		words_array.push words_array.shift # .. value found at the back of
the first array
	end
	words_array.pop				# remove the last value contained within the 1st
array
	rotateCounter = 0			# reset rotate counter
	wordCheck = words_array.last 		# replace current value of wordCheck
with new last word from 1st array
end
puts sortedWords_array	# print values within 2nd array, which should
be in low to high alphabetical order

# Hope the above is legible