From: James Edward Gray II <james@...>
Date: 2006-04-20T02:55:07+09:00
Subject: Re: Probleme with 2-dimensionnal arrays

On Apr 19, 2006, at 11:03 AM, Erard Sebastien wrote:

> I can't understand why this piece of code doesn't return the array
> expected ?
>
> my_array = Array.new(3, Array(3))

my_array = Array.new(3) { Array.new }

> 3.times do |i|
>   3.times do [j|
>     my_array[i][j] = i + j
>   end
> end
>
> it should return :
> [[ 0, 1, 2] [1, 2, 3] [2, 3, 4]]
>
> but it returns :
> [[2, 3, 4] [2, 3, 4] [2, 3, 4]]
>
> Is my code wrong ?

The two argument form of the constructor uses the same object in each  
slot.  Thus, if you change one, all are modified.  The block form I  
used above will be called to generate each object, getting you the  
desired results.

Hope that helps.

James Edward Gray II