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•Re: array index -1 oddity

by merlyn (Sage)
on Dec 06, 2002 at 18:33 UTC ( #218122=note: print w/replies, xml ) Need Help??

in reply to array index -1 oddity

I would have thought that trying to assign to the -1 element in an uninitialized array would assign to element 0, but i guess not.
I would call that unexpected.

Assigning to element -1 assigns to the highest element in the array. You have an empty array. There is no "highest element". That's out of range.

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

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Re: •Re: array index -1 oddity
by scain (Curate) on Dec 06, 2002 at 19:07 UTC
    Really? That strikes me as a little odd and counter-intuitive. There are instances where having an array index of -1 (or -2 or -3) are quite useful. In particular, some numerical methods come to mind. I suppose that if I felt like doing that, I would need to modify a magic variable first? Like $[ if I read man perlvar correctly.

    Project coordinator of the Generic Model Organism Database Project

      Maybe you missed this statement in perldata:
        Variable names
          Perl has three built-in data types: scalars, arrays of scalars, and
          associative arrays of scalars, known as "hashes". Normal arrays are
          ordered lists of scalars indexed by number, starting with 0 and with
          negative subscripts counting from the end. Hashes are unordered
          collections of scalar values indexed by their associated string key.

      -- Randal L. Schwartz, Perl hacker
      Be sure to read my standard disclaimer if this is a reply.

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