That's not very complicated:

Well, maybe, but you are not asking the OP. That is: "I need a regular expression to match the following pattern.". You are using 2. (and perliff above uses 3!).

Update: Solving the problem with 2+ regexps is more or less trivial, but using just 1 is far more interesting. Here is a solution using look-ahead assertions (see perlre):

my $re = qr{ ^           # match at the beginning.
             (?!         # Look-ahead assertion: Fail if the next matc
+hes
               .* first  # match "first" everywhere except at the begi
+nning of the string
             )           # end of look-ahead assertion
             This .* \.  # Match "This" (at the beginning), followed b
+y anything and a dot
             $           # Match the end of a string.
         }x;             # Allow these comments

[download]

citromatik

In reply to Re^2: Reguar expression by citromatik
in thread Reguar expression by selva

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.