From: "Wayne E. Seguin" <wayneeseguin@...>
Date: 2007-09-29T20:46:01+09:00
Subject: Re: Noobie question: saving the values

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On 9/29/07, Druhie Almighty <squeezzed@gmail.com> wrote:
>
> So can you please explain me why do these two operations very close to
> each other result in different ways, considering the fact that both a
> and b contain the same link?
>
> 1)
> a="13"
> b=a
> a="12"
> puts b --> 13
>
> 2)
> a="13"
> b=a
> a[1]="2"
> puts b --> 12


You're first way makes 'a' point at a new string object "12".


It appears that you are thinking of C strings :) Strings in Ruby are a bit
different. You can access individual characters using the [] operator.
Indexes are 0 based so when you did a[1] where a was a string, you were
assigning the number '2' to the second position in the string, hence
overwriting the '3'.


What you were probably intending to do was something like this:

>> a = [ "13" ]
=> ["13"]

>> b = a
=> ["13"]

>> a[1] = 2
=> 2

>> a
=> ["13", 2]

Also note that the reason this change reflected when you printed out 'b' is
because after the assignment "b=a", 'b' will refer to the variable 'a'.
Meaning it does not create a new object but instead becomes a name for the
old so that both 'a' and 'b' are both names for the same object.



Other ways you can append elements to the end of the array:
>> a << "3"
=> ["13", 2, "3"]

>> a.push "4"
=> ["13", 2, "3", "4"]

You can checkout the Array methods available to you here:
http://www.ruby-doc.org/core/classes/Array.html

I hope this helps,

  ~Wayne

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