Re: grouping in regex

[Rob Dixon]

On 23/12/2012 13:27, punit jain wrote:
Hi,
I am doing grouping but seeing some weird behavior :-

the strings in a file are like :-
AccessModes =
(18,Mail,POP,IMAP,PWD,WebMail,WebSite,Relay,Mobile,FTP,MAPI,TLS,LDAP,WebCAL);
....
...
.
multiple lines

I am seeing which lines have both POP and Webmail as below :-

if( $line =~ /AccessModes\s*=\s*.*(WebMail)*.*(POP).*(WebMail)*.*/ ) {
                             if(defined $2) {
                                 print "$2 $1"."$line"."\n";
                             }
                         }


However I get these below :-

   POPUse of uninitialized value in concatenation (.) or string at
test.plline 283, <GEN85> line 2.
   POPUse of uninitialized value in concatenation (.) or string at
test.plline 283, <GEN86> line 2.
   POPUse of uninitialized value in concatenation (.) or string at
test.plline 283, <GEN87> line 2.

Any clue why ?

You would be bettre off using a look-ahead, which doesn't care what
order the two options appear in the list. The program below shows an
example.

Rob

use strict;
use warnings;

while (my $line = <DATA>) {
  if ($line =~ /AccessModes\s*=\s*(?=.*(\bPOP\b))(?=.*(\bWebMail\b))/) {
    print "$1 $2\n";
  }
}


__DATA__
AccessModes = 
(18,Mail,POP,IMAP,PWD,WebMail,WebSite,Relay,Mobile,FTP,MAPI,TLS,LDAP,WebCAL);
AccessModes = 
(18,Mail,IMAP,PWD,WebMail,WebSite,Relay,Mobile,FTP,MAPI,TLS,LDAP,POP,WebCAL);

**output**

POP WebMail
POP WebMail


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