perldoc perldata would have told you that $# means 'the last index of array'. In this case, it's the last index of the array referenced by $some_var[$i].

See also: References quick reference.

In reply to Re: where to look up "funny looking" perl notation (and an example) by Mr. Muskrat
in thread where to look up "funny looking" perl notation (and an example) by glwtta

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