Maybe something like: 

c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = '1 x 12 x 123 x 1234 x 12345 x 123 x 1234 x';
 print qq{'$s'};
 ;;
 $s =~ s{ \b (\d{3,4}) \b }{<a $1><b>$1</b></a>}xmsg;
 print qq{'$s'};
"
'1 x 12 x 123 x 1234 x 12345 x 123 x 1234 x'
'1 x 12 x <a 123><b>123</b></a> x <a 1234><b>1234</b></a> x 12345 x <a
+ 123><b>123</b></a> x <a 1234>
<b>1234</b></a> x'

[download]
(with the HTML tags simplified). I.e., just make one substitution pass through the string instead of many.

Update: Or did you mean that you do not want the second instances of '123' or '1234' in the string to be en-tag-ified?

Give a man a fish:  <%-(-(-(-<

In reply to Re: Recognizing numbers and creating links by AnomalousMonk
in thread Recognizing numbers and creating links by htmanning

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.