From: Kent Sibilev <ksruby@...>
Date: 2005-06-18T09:04:28+09:00
Subject: Re: Why do arrays work this way?

When you make an assignment b = a, you assign the variable 'b' a
reference to the same array variable 'a' refers to. If you want to
have a copy of array a use dup method like

b = a.dup

Kent.


On 6/17/05, Nigel Wilkinson <nigel@waspz.co.uk> wrote:
> Hi folks
> 
> I'm using ruby 1.8.2 as comes with Mandriva 2005LE and get the following
> behaviour with arrays which doesn't seem logical to me.
> 
> In irb I do
> 
> irb(main):058:0* a=[1,2,3,4,5]
> => [1, 2, 3, 4, 5]
> 
> straight forward enough
> 
> irb(main):059:0> b=a
> => [1, 2, 3, 4, 5]
> irb(main):060:0> c=a
> => [1, 2, 3, 4, 5]
> 
> I've set 2 more variables to equal 'a'
> 
> irb(main):061:0> b[3] = 'w'
> => "w"
> 
> I believe this changes index 3 in'b' to now be equal to 'w'
> 
> do
> irb(main):062:0> b
> => [1, 2, 3, "w", 5]
> 
> that's exactly as I expected, BUT
> 
> irb(main):063:0> a
> => [1, 2, 3, "w", 5]
> irb(main):064:0> c
> => [1, 2, 3, "w", 5]
> 
> so what's the logic behind 'a' & 'c' changing when I change 'b'.
> 
> Is this a bug? and if not what's the reasoning behind this behaviour please.
> 
> 
> 
> Best Rgds from confused of Heathfield
> Nigel
> __________________________________________________________________________
> Disclaimer
> Any opinions expressed in this email are not necessarily those of my wife
> 
>