From: Fedor Labounko <fedor.labounko@...>
Date: 2007-03-17T06:29:47+09:00
Subject: Re: Issues using array.delete within a loop of the same array

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Now this is pure speculation on my part and I'm not offering a solution to
the problem, rather a likely explanation. The other solutions all look good
to me as alternatives.

It would make sense that what Array#each is doing behind the scenes is
simply using an index and a for loop up to the size of the array, and then
passing you a[i]. So then during the first step you delete a[0], which
renumbers the elements in the array. During the second step you delete a[1],
which is now actually 3, since that's now the second element in the array.
Continue in this manner you'll skip every other element in the array.

On 3/16/07, james.d.masters@gmail.com <james.d.masters@gmail.com> wrote:
>
> This is a simplified example for what I'm trying to do but gets the
> point across:
>
> irb(main):001:0> a = [1,2,3,4,5]
> => [1, 2, 3, 4, 5]
> irb(main):002:0> a.each {|e| a.delete e}
> => [2, 4]
>
> I would expect the array to be emptied.  Insight please...
>
> Yes, I know that there are other ways to empty an array (i.e. a =
> []).  My code is more complex and I'm more interested in why this is
> happening and if there is a work-around for removing array items while
> iterating over the same array.  There will be other cases in this code
> where I will only want to remove some of the items.
>
> Thanks in advance...
>
>
>

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