I have understood that using regex for this problem is not the preferred method, at all. It was however my intention to learn more about regexp, so for now, with your help I have come up with (using the backwards strategy) 

# First match !
    $data =~ s|^(.*<section1>.*<rstate>).+(</rstate>.*</section1>.*)$|
+$1$newrstate$2|s;

# Second match!
    $data =~ s|^(.*<section2>.*<rstate>).+(</rstate>.*</subsection>.*<
+/subsection>.*</subsection>.*</section2>.*)$|$1$newrstate$2|s;

# Third match!
    $data =~ s|^(.*<section3>.*<rstate>).+(</rstate>.*</section3>.*)$|
+$1$newrstate$2|s;

[download]

Curious as I am, I will read up on the XML parser and try it as well to see how it compares. Thanks for the help!

In reply to Re^2: regex: Need help substituting by the_perl
in thread regex: Need help substituting by the_perl

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.