Beefy Boxes and Bandwidth Generously Provided by pair Networks
Your skill will accomplish
what the force of many cannot
 
PerlMonks  

comment on

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

If you want a list of all two letter patterns that appear at least twice somewhere in your string, you need to make three changes to your regex.

  1. you need to make (\w{2,}) non-greedy by adding a "?" to the end, e.g. (\w{2,}?).
  2. you need to wrap what comes after (\w{2,}?) with a zero width lookahead group. Otherwise you will miss all the matches between the first and second occurrence of "ab"
  3. you need to handle repetitions of your regex slightly differently. Instead of /( mumblefoo )+/ you need /mumblefoo/g. Using a + the way you did will only get you the last match found because each time the + causes the regex to repeat, it replaces the previous match.

Taken together these changes will make your regex will look like this: /(\w{2,}?)(?=.*?\1)/g:

print $x = "abcdefgxxabcdefgzzabcdsjfhkdfab", "\n"; print "<" . join('|',$x =~ /(\w{2,}?)(?=.*?\1)/g) , ">\n"; #outputs: <ab|cd|ef|ab|cd|ab>

You can more info on zerolength lookaheads via the Extended Patterns section of the perlre manpage on perldoc


In reply to Re: RegEx + vs. {1,} by ELISHEVA
in thread RegEx + vs. {1,} by Sewi

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

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

How do I use this? | Other CB clients
Other Users?
Others romping around the Monastery: (1)
As of 2021-10-24 01:34 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    My first memorable Perl project was:







    Results (88 votes). Check out past polls.

    Notices?