Re: Strangness with arrays

The problem is with the

   for (@array)
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bit. Under normal circumstances, the array is flattened into a list and you can then mess with @array safely. However... there's an optmization in perl such that if the only thing in the list is a plain array then perl doesn't flatten, it just whips through the array, and modifying the array has... Interesting Results.

If you want, you can throw another set of parens around @array to force it to be a list, then you can mess with it as much as you like within the loop without really messing things up.

Comment on Re: Strangness with arrays Download Code

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Re^2: Strangness with arrays by Aristotle (Chancellor) on Jul 10, 2002 at 20:41 UTC
Actually, the loop variable is always aliased to the loop elements, even when you say something like `for (@a1, @a2, @a3)` or even `for (qw(foo bar baz 1 2 3), @a1)`. If you really want to force flattening, you need to force a copy of the data structure: `for(@{[@a1, @a2, @a3]})` Update: point taken. Makeshifts last the longest.	[reply] [d/l] [select]
Re: Re^2: Strangness with arrays by Elian (Parson) on Jul 10, 2002 at 21:01 UTC
You misunderstood. Yes, the loop variable always aliases to the individual scalars. This is true. But in the case presented, with a bare, single array in for/foreach's list, perl also turns the loop into an iteration over the array itself, rather than flattening the array and iterating over the list of scalars.	[reply]