can i get a matched values as an array

balakrishnan has asked for the wisdom of the Perl Monks concerning the following question:

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Re: can i get a matched values as an array by irah (Pilgrim) on Feb 17, 2009 at 08:39 UTC
Here I give the example, `@words = ($str =~ /(\w+)/g);` [download] The array have a words from index 0. If it is three words, each word will be in each index from 0 to 2. I got this information from perlrequick. Further more information look into the man page.	[reply] [d/l]
Re: can i get a matched values as an array by AnomalousMonk (Archbishop) on Feb 17, 2009 at 08:41 UTC
This can be done by capturing a match to an array: `>perl -wMstrict -le "my $s = 'age 23 name john'; my @an = $s =~ m{ age \s+ (\d+) \s+ name \s+ ([a-z]+) }xms; print qq{@an}; " 23 john` [download] Note that if there is an overall match, each capturing group of the regex will return something to the array even if that particular group was not a part of the overall match: `>perl -wMstrict -le "my $s = 'age 23 name john'; my @an = $s =~ m{ name \s+ ([a-z]+) \| address \s+ (\d+) }xms; my $captured = join ':', @an; print qq{:$captured:}; " Use of uninitialized value in join or string at -e line 1. :john::` [download] The values from unmatched capture groups are undefined and can be detected and filtered: `>perl -wMstrict -le "my $s = 'age 23 name john'; my @an = $s =~ m{ name \s+ ([a-z]+) \| address \s+ (\d+) }xms; defined or $_ = 'UNdefined' for @an; my $captured = join ':', @an; print qq{:$captured:}; " :john:UNdefined:` [download] See perlop, the section on Regexp Quote Like Operators, subsection on the m/PATTERN/msixpogc operator, about the seventh paragraph in. Note: in Perl 5.10, this can also be done with named capture buffers. Look for `(?<NAME>pattern)` in perlre Extended Patterns. Updates: Added reference links. Added note re: named capture buffers.	[reply] [d/l] [select]
Re: can i get a matched values as an array by gone2015 (Deacon) on Feb 17, 2009 at 14:50 UTC
BTW, your: `$str =~ s/age ([0-9]+) name ([a-z]+)/$&/ ;` [download] is matching something and then replacing it by itself. Not only does this seem a little pointless (why not just `m/age ([0-9]+) name ([a-z]+)/` ?), but the documentation warns that: The use of this variable anywhere in a program imposes a considerable performance penalty on all regular expression matches. so using `$&` when you don't absolutely need it looks like a mistake...	[reply] [d/l] [select]
Re: can i get a matched values as an array by Utilitarian (Vicar) on Feb 17, 2009 at 08:49 UTC
Hi balakrishnan, To the best of my knowledge you can't use a substitution. however you could use split to achieve this. `#!/usr/bin/perl use strict; my $i; my @values; my $string ="age 42 name Utilitarian FamilyName"; ($i,@values)= split(/age\|name/, $string); for ($i=0;$i<@values;$i++){ print "$i, $values[$i]\n"; }` [download] This is ugly, but does what you want in one step (ie.applies the regex and makes the matches available in an array.	[reply] [d/l]