From: "Aaron D. Gifford" <astounding@...>
Date: 2011-12-20T05:10:05+09:00
Subject: Re: Understanding array.clear

On Mon, Dec 19, 2011 at 12:48 PM, Nick Sandberg <nss118@gmail.com> wrote:
> I was working a project Euler problem and noticed that when I used this
> code:
>
> array1 = ["a", "b", "c", "d", "e"]
> array2 = Array.new
> array2 << array1

You just stored the object array1 inside of array 2.

> array1.clear

Having cleared array1 (emptied it out) by calling the Array instance
in array1's clear method...

> p array2
>
> [[]] is my output. But, when I tried:

...you see the expected output, since the array1 object is now empty.

>
> array1 = ["a", "b", "c", "d", "e"]
> array2 = Array.new
> array2 << array1
> array1 = []

Here you are NOT clearing out array1, but assigning a brand new array
object to the variable array1.  So the old array1 is still in
existence (and still stored in array2).

> p array2
>
> [["a", "b", "c", "d", "e"]] is my output.  I am not understanding why
> clearing array1 is changing array2, but replacing the value of array1 is
> having no effect.

I hope this clears it up a bit.

<<snip>>

Aaron out.