I'm not as clever as some, so I did it the long way... 
#!/usr/bin/perl

use strict;
use warnings;

while( my $ln = <DATA> )
  {
    chomp( $ln );

    my @flds = split( '@', $ln );
    foreach ( @flds )
      {
        if ( /(#*)/ )
          { 
            print "/$ln/ --> /$1/\n" if ( length( $1 ) % 2 ) == 1;
          }
      }
  }

__DATA__
#@##@###@####@#####@
#@##
###@####
#####@

[download]

This results in: 

/#@##@###@####@#####@/ --> /#/
/#@##@###@####@#####@/ --> /###/
/#@##@###@####@#####@/ --> /#####/
/#@##/ --> /#/
/###@####/ --> /###/
/#####@/ --> /#####/

[download]
Revised: This won't work for a string with no pound signs. You'd need to modify the length test to include  || length( $1 ) == 0.

In reply to Re: Splitting on escapable delimiter by apl
in thread Splitting on escapable delimiter by Daryn

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.