Regexp a reverse-d string?

Are there any idioms or common scenarios when you first reverse the string before matching?

$ perl -wle 'reverse("abcd") =~ /(cb)/; print $1' 
cb
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I remember a friend doing this in a Tcl because it didn't have non-greedy quantifiers. (I wish I could remember the details... It was a very long time ago)

Comment on Regexp a reverse-d string? Download Code

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Re: Regexp a reverse-d string? by jmcnamara (Monsignor) on Apr 14, 2003 at 08:29 UTC
Japhy calls this a sexeger. Anyone who hasn't seen this technique should read the above node. It has many useful and interesting applications. See also Reversing Regular Expressions by Pete Sergeant on perl.com. -- John.	[reply]
(jeffa) Re: Regexp a reverse-d string? by jeffa (Bishop) on Apr 14, 2003 at 16:34 UTC
The Perl Cookbook uses this technique for recipe 2.17, Putting Commas in Numbers: `sub commify { my $text = reverse $_[0]; $text =~ s/(\d\d\d)(?=\d)(?!\d*\.)/$1,/g; return scalar reverse $text; }` [download] jeffa L-LL-L--L-LL-L--L-LL-L-- -R--R-RR-R--R-RR-R--R-RR B--B--B--B--B--B--B--B-- H---H---H---H---H---H--- (the triplet paradiddle with high-hat)	[reply] [d/l]