Beefy Boxes and Bandwidth Generously Provided by pair Networks
laziness, impatience, and hubris

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??

I'm confused with a negative lookahead. Here's some example code. I want it to match on $needs and to not match on $has. The examples 3 and 4 are only as a reference to a fixed string, but I basically want ^($start(.*?))(?!$end)$. Any ideas?

#!/usr/bin/perl use strict; use warnings; my $start = "log4j.rootLogger="; my $startlong = "log4j.rootLogger=INFO, FILE"; my $end = ", SYSLOG"; my $needs = 'log4j.rootLogger=INFO, FILE'; my $has = $needs . ', SYSLOG'; print "needs_matched $needs\n" if $needs =~ /^($start(\w+(,\s)?)+)(?!$ +end)$/; print "has_matched $has\n" if $has =~ /^($start(\w+(,\s)?)+)(?!$end)$/ +; print "needs_matched $needs\n" if $needs =~ /^(log4j.rootLogger=INFO, +FILE)(?!, SYSLOG)$/; print "has_matched $has\n" if $has =~ /^(log4j.rootLogger=INFO, FILE)( +?!, SYSLOG)$/;


In reply to regex: negative lookahead by svenXY

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!
  • 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, 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, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            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.
  • Log In?

    What's my password?
    Create A New User
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others chilling in the Monastery: (9)
    As of 2015-03-06 06:04 GMT
    Find Nodes?
      Voting Booth?

      When putting a smiley right before a closing parenthesis, do you:

      Results (157 votes), past polls