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| author | Rafael Garcia-Suarez <rgarciasuarez@gmail.com> | 2005-08-17 15:57:09 +0000 |
|---|---|---|
| committer | Rafael Garcia-Suarez <rgarciasuarez@gmail.com> | 2005-08-17 15:57:09 +0000 |
| commit | e341a03b020a518de4997e2f36fb98e94f3390f0 (patch) | |
| tree | 7b5153ce44a42fc4841ed7592ea2e01baf4f3c4b /pod/perlfaq6.pod | |
| parent | 9b91f3510d4bb5b52d8088c11adb81519f2fe9db (diff) | |
| download | perl-e341a03b020a518de4997e2f36fb98e94f3390f0.tar.gz | |
FAQ sync
p4raw-id: //depot/perl@25301
Diffstat (limited to 'pod/perlfaq6.pod')
| -rw-r--r-- | pod/perlfaq6.pod | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/pod/perlfaq6.pod b/pod/perlfaq6.pod index a9e04a98f0..ed0bc29741 100644 --- a/pod/perlfaq6.pod +++ b/pod/perlfaq6.pod @@ -1,6 +1,6 @@ =head1 NAME -perlfaq6 - Regular Expressions ($Revision: 1.32 $, $Date: 2005/04/22 19:04:48 $) +perlfaq6 - Regular Expressions ($Revision: 1.35 $, $Date: 2005/08/10 15:55:08 $) =head1 DESCRIPTION @@ -633,14 +633,20 @@ These strings do not match /\Bam\B/ (contributed by Anno Siegel) Once Perl sees that you need one of these variables anywhere in the -program, it provides them on each and every pattern match. That means -that on every pattern match the entire string will be copied, part of -it to $`, part to $&, and part to $'. Thus the penalty is most severe -with long strings and patterns that match often. Avoid $&, $', and $` -if you can, but if you can't, once you've used them at all, use them -at will because you've already paid the price. Remember that some -algorithms really appreciate them. As of the 5.005 release, the $& -variable is no longer "expensive" the way the other two are. +program, it provides them on each and every pattern match. That means +that on every pattern match the entire string will be copied, part of it +to $`, part to $&, and part to $'. Thus the penalty is most severe with +long strings and patterns that match often. Avoid $&, $', and $` if you +can, but if you can't, once you've used them at all, use them at will +because you've already paid the price. Remember that some algorithms +really appreciate them. As of the 5.005 release, the $& variable is no +longer "expensive" the way the other two are. + +Since Perl 5.6.1 the special variables @- and @+ can functionally replace +$`, $& and $'. These arrays contain pointers to the beginning and end +of each match (see perlvar for the full story), so they give you +essentially the same information, but without the risk of excessive +string copying. =head2 What good is C<\G> in a regular expression? |