The first syntax: $#{@alarms} isn't much good for anything beyond obfuscation, and shouldn't pass strictures. I don't know if it worked in some way that it shouldn't have back when Perl 5.8.8 was current, but here's what I think it is, deobfuscated nowadays:

@alarms in scalar context will yield the number of elements in @array. Let's say you have one element. So it returns the number 1.

$#{....} will attempt to either dereference '....', or if it's not a reference, use '....' as a symbol. In this particular example, '....' happens to be the string '1'. '1' comes from the number of elements in @array.

Using '1' as a symbol, and placing a $# sigil in front of it, you now have a symbolic reference. You're asking Perl what the highest index is in the array named @1. I can't think of any reason that there would be an array named @1, but it probably doesn't have any practical relationship to @array, so the code in your first example is useless.

The usage is far enough off the beaten path that I could be wrong about how it's parsed, but that seems reasonable to me at the moment.


Dave

In reply to Re: understanding curly braces surrounding an array by davido
in thread understanding curly braces surrounding an array by kionysus

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.