Hi Anonymous,

You can't use more than one statement modifier like for or if at a time (and I think that if you were able to, it would lead to more hard-to-understand code). If your code gets more complex you should instead use a normal for loop:

for my $n (qw/1 12 123 234/) {
    print "$n =>\n" if $n=~/1/;
}

[download]

(Ok, there is a way to do what you want, but legibility begins to suffer if it gets longer: /1/ and print "$_ =>\n" for qw/1 12 123 234/;)

Update: I should add that I was golfing a little bit in my example code, and that compressed style is not necessarily something one should strive to use in production code ;-)

Regarding the other question about (??{ }), that's documented along with (?{ }) in perlre. The oversimplified explanation is that the code inside (??{...}) is evaluated and its return value embedded as part of the regular expression (but make sure to read the docs). So in my regex, the code '.{'.length($2).'}' takes the length of the string matched in between the first set of x's (x(.*)x), and then generates an expression like .{N} (where N is the length), so if the input were x12345x67890x, the regular expression it is matched against is x.*x.{5}x.

Hope this helps,
-- Hauke D

Updated wordings a little bit.

In reply to Re^3: Regular Expression: search two times for the same number of any signs (updated) by haukex
in thread Regular Expression: search two times for the same number of any signs by Anonymous Monk

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.