grain_of_sand has asked for the wisdom of the Perl Monks concerning the following question:
I am trying to debug my understanding of the matching operator.
When invoked with the g modifier in list context, I thought that
the return value is a list of all possible matches. If capturing
parentheses are used, then the list is the set of all $1, $2, etc
captured.
The following bit of Perl:
I have read the Camel book chapter on this & the perlop man page, but they don't really have a lot to say about this...
grain_of_sand
The following bit of Perl:
prints out:#!/bin/perl -w $" = '-'; $string = "a:b c:d"; @list = ($string =~ m/(\w):(\w)/g); print "list=@list\n"; $string = "a:b:c"; @list = ($string =~ m/(\w):(\w)/g); print "list=@list\n";
I understand the first line of output, but it seems to me that the second line of output should really be:list=a-b-c-d list=a-b
This is because the (\w):(\w) can match a:b and also b:c. It appears that the regex engine finds the first match of a:b and then starts the next matching attempt after the b, in which case it cannot find the b:c match. I expected the next matching attempt to start after the a, so that the b:c match would also be found.list=a-b-b-c
I have read the Camel book chapter on this & the perlop man page, but they don't really have a lot to say about this...
grain_of_sand
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Replies are listed 'Best First'. | |
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Re: m//g in list context
by dws (Chancellor) on Aug 08, 2002 at 21:30 UTC | |
•Re: m//g in list context
by merlyn (Sage) on Aug 08, 2002 at 22:17 UTC | |
Re: m//g in list context
by Zaxo (Archbishop) on Aug 08, 2002 at 21:31 UTC |
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