From: Victor Reyes <victor.reyes@...>
Date: 2008-04-07T09:43:20+09:00
Subject: Re: Problem while printing the content of an array, which is pointed by a variable

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Stefano,

Thank you for your suggestion and sample code.
I will use it.

Thanks again,

Victor

On Sun, Apr 6, 2008 at 12:18 PM, Stefano Crocco <stefano.crocco@alice.it>
wrote:

>  On Sunday 06 April 2008, Victor Reyes wrote:
> > Team,
> >
> > I am trying to print the content of array, which is "addressed?" by a
> > variable.
> > Instead of getting the content of the array, I am getting its name.
> > I think it is better to take a look at the code bellow.
> PLEEEEEEEEEEEEEASE
> > Do not laugh at my code, I'm still a beginner!
> >
> > For example, for array @a1h, I expected to see: 1,0,0,0,7,0,0,0,4 but
> > instead I see: @a1h.
> >
> > class SudokuBrute
> >     def initialize
> >
> >     # The following sudoku is from:
> > http://www.life.com/Life/sudoku/0,26379,,00.html
> >     # This puzzle is rated as: easy
> >     @a1h = [1,0,0,0,7,0,0,0,4]
> >     @a2h = [0,0,0,6,0,4,0,5,0]
> >     @a3h = [0,0,8,0,9,0,0,0,0]
> >     @a4h = [6,0,0,9,0,0,0,1,5]
> >     @a5h = [0,1,9,0,0,0,7,4,0]
> >     @a6h = [5,3,0,0,0,1,0,0,8]
> >     @a7h = [0,0,0,0,4,0,3,0,0]
> >     @a8h = [0,7,0,5,0,8,0,0,0]
> >     @a9h = [4,0,0,0,6,0,0,0,1]
> >     end # End method initialize
> >
> >   def pGrid
> >      for
> >       x in 1..9 do
> >         for
> >           i in 1..9 do
> >             arr = "@a" + i.to_s + "h"
> >             puts arr
> >         end
> >     end
> >   end  # End of method pGrid
> > end    # End Class
> >
> > class Array
> >   include Comparable
> > end
> >
> > ##################
> > ms = SudokuBrute.new
> >
> > # Output initial settings
> > ms.pGrid
>
> Well, it's doing what you're asking it to do. arr is not an array, it's a
> string like "@a1h". To achieve what you want, you can use
> instance_variable_get, which returns the content of the instance variable
> whose name is passed as argument:
>
> arr = "@a" + i.to_s + "h"
> puts instance_variable_get(arr)
>
> The above suggestion works and only requires a small change in your code.
> Most
> likely, though, you should rethink the design of your class, replacing the
> nine instance variables with a single hash or array variable, like this:
>
> @a = {
>  :a1h => [1,0,0,0,7,0,0,0,4],
>  :a2h => [0,0,0,6,0,4,0,5,0],
>  :a3h => [0,0,8,0,9,0,0,0,0],
>  :a4h => [6,0,0,9,0,0,0,1,5],
>  :a5h => [0,1,9,0,0,0,7,4,0],
>  :a6h => [5,3,0,0,0,1,0,0,8],
>  :a7h => [0,0,0,0,4,0,3,0,0],
>  :a8h => [0,7,0,5,0,8,0,0,0],
>  :a9h => [4,0,0,0,6,0,0,0,1]
> }
>
> This stores the content of the grid into a hash, where each entry
> represents a
> row. The keys are symbols (you can replace them with strings, if you like)
> and
> correspond to the names you gave to your instance variables. You can
> access a
> row with:
>
> row = @a[:a3h]
>
> The downside of using a hash is that entries aren't ordered. If you need
> to
> iterate on all the rows in order, this isn't the best solution. In this
> case,
> I'd use an array:
>
> @a = [
>  [1,0,0,0,7,0,0,0,4],
>  [0,0,0,6,0,4,0,5,0],
>  [0,0,8,0,9,0,0,0,0],
>  [6,0,0,9,0,0,0,1,5],
>  [0,1,9,0,0,0,7,4,0],
>  [5,3,0,0,0,1,0,0,8],
>  [0,0,0,0,4,0,3,0,0],
>  [0,7,0,5,0,8,0,0,0],
>  [4,0,0,0,6,0,0,0,1]
> ]
>
> This way, rows can be accessed sequentially in the correct order, using
> @a.each or the for ... in syntax you used above . You can also access them
> using the [] syntax:
>
> @a[3]
>
> The downside is that you can no longer associate a key with the items.
>
> I hope this helps
>
> Stefano
>
>

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