Without any known structure of the text there is no easy solution.

(Example: A non-matching closing parenthesis could be Which ones are the non-matching ones?)

This block of text has one opening and four closing parentheses. A naive matching could match '(Example' with '1.)' and mark those in '2.)', ':-)' and 'ones?)' as non-matching, but that's probably not what you want. Here are some other edge cases:

With a module like XML::LibXML::Reader you can traverse an XML document and keep track of the current parentheses level, reporting whenever the level is decreases below 0. However, in my opinion such XML processing does not qualify as "easy".

In reply to Re: Finding parentheses that won't match by haj
in thread Finding parentheses that won't match by LexPl

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.