From: Vladimir Fekete <fekete@...>
Date: 2008-11-28T08:08:06+09:00
Subject: Re: Programming Noob Chris Pine Tutorial sorting without use of array.sort method

Hi,

   so If I'm correct what you are looking for is mistake in your sort code,
right? (because - to be honest, I don't really understand why (except make
it an excercise for you) you do not look in google for sorting algorithms.
One you described looks similar to Bubble sort. There are many others, bubble
sort is most easies one and very slow but easy to implement.)

Regards

   V.


On Fri, Nov 28, 2008 at 06:30:09AM +0900, whisperjim wrote:
> I'm working through the following tutorial http://pine.fm/LearnToProgram/
> (recommended by the official Ruby site)
> as a starting point and I've got to chapter 7 and struggling with  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? "
> 
> Now I'm supposed to do this without any .sort method and the chapters
> I've covered so far (1 ~ 7) have not covered method creation,
> Classes,Blocks or Procs, so the challenge is to solve the assignment
> without using them.
> 
> Now I've written a program but I think the basic 'mental model' is
> flawed, I say this because of the results I'm getting.
> 
> If I use the following input [ q w e r t y ] I end up with [ e q r t w
> w ] and the input [ z x c v b ] end up as [ b b b b b ].
> 
> If my mental model is o.k, then my code must be wrong, but I'm stumped
> at to where.
> 
> # concept - store words in 1st array (words_array). Find the
> 'smallest' word alphabetically by selecting the last word (call it
> wordCheck) and compare 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 first unsorted
> 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
> 
> Guidance greatly appreciated.
> 
>