John W. Krahn wrote:
Aruna Goke wrote:
Chris E. Rempola wrote:
How would you match Parenthesis in Perl?
- STRING -
Received: from 10.143.205.68.abc.def.gh.com (10.205.143.238)
- /STRING -
I want to be able to grab the IP address in (10.205.143.238).
Thanks in advance.
#/usr/bin/perl
use warnings;
use strict;
#use re 'debug';
my $f = "Received: from 10.143.205.68.abc.def.gh.com (10.205.143.238)";
print $&, if $f=~m/\S+$/;
perldoc perlre
[ snip ]
WARNING: Once Perl sees that you need one of $&, $`, or $' anywhere
in the
program, it has to provide them for every pattern match. This may
^^^^^^^^
substantially slow your program. Perl uses the same mechanism to
produce
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
$1, $2, etc, so you also pay a price for each pattern that contains
capturing parentheses. (To avoid this cost while retaining the
grouping
behaviour, use the extended regular expression "(?: ... )"
instead.) But
if you never use $&, $` or $', then patterns without capturing
parentheses
will not be penalized. So avoid $&, $`, and $' if you can, but if you
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
can’t (and some algorithms really appreciate them), once you’ve used
them
once, use them at will, because you’ve already paid the price. As of
5.005, $& is not so costly as the other two.
Why is there a comma after the variable? Did you forget to include
another variable?
John
Thanks John,
I have noted the explanation.
Goksie
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