You are getting empty strings (not undefs) because of your capturing parentheses. As it says in split
If the PATTERN contains parentheses, additional list elements are created from each matching substring in the delimiter.

From how you've coded that, your split values are actually '' and your delimiters are the elements you are interested in.

Better is subjective, but I might do the split on any character followed by an A:

@parts=split(/(?=A)/,"A2ABA45");

You could also use a regular expression with the g modifier in list context and no capturing:

@parts = "A2ABA45" =~ /A[^A]*/g

That is less obvious to the neophyte, though. See Global matching.

In reply to Re: repeated regex capture by kennethk
in thread repeated regex capture by twilliamsark

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.