Is this a regex strangeness?

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

Am I just crazy today, or is the behavior of this one-liner strange?

echo 'abcdef g' | perl -e '$_ = <>; print if m/[a-g]+\n/'
[download]

It prints the line. Should it? What's matching the space?

Here's my perl -v:

# perl -v This is perl, v5.8.7 built for i686-linux-ld Copyright 1987-2005, Larry Wall Perl may be copied only under the terms of either the Artistic License or the GNU General Public License, which may be found in the Perl 5 source kit. Complete documentation for Perl, including FAQ lists, should be found on this system using `man perl' or `perldoc perl'. If you have access to the Internet, point your browser at http://www.perl.org/, the Perl Home Page.

Christopher E. Stith

Comment on Is this a regex strangeness? Download Code

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Re: Is thie a regex strangeness? by ikegami (Patriarch) on Jan 31, 2006 at 18:41 UTC
Replace `m/[a-g]+\n/` with `m/^[a-g]+\n$/` It was matching the `"g\n"` part of the input string. By the way, it's `<code>` (or `<c>`), not `[code]`.	[reply] [d/l] [select]
Re^2: Is thie a regex strangeness? by mr_mischief (Monsignor) on Jan 31, 2006 at 19:26 UTC
Ah! How embarrassing. Yes, that makes perfect sense. It's been an off-kilter day all around. Sorry for the tag confusion on my part. I've been mostly away from the site for a long while. Christopher E. Stith	[reply]
Re: Is this a regex strangeness? by blazar (Canon) on Feb 01, 2006 at 10:55 UTC
Indeed it matches a sequence of one or more charachters in the range `[a-g]` next to the newline. Precisely `"g\n"`. In case of doubt although there's a case against `$&` ;-) you may try printing that to see what matched. Or else put a pair of capturing parens and print `$1` which amounts to fundamentally the same thing. Or even use the return value of the match: `$ perl -pe '($_)=/[a-g]+\n/g' abcdef g g` [download]	[reply] [d/l] [select]