On Tue, Sep 15, 2009 at 2:43 AM, Philip Hazel <[email protected]> wrote: > Meanwhile, here is a palindrome-matching pattern > that I was sent some years ago; it differs from your requirements > because it ignores spaces and punctuation, and looks only at word > characters. I don't know how it works, but it recognizes palindromes > such as "A man, a plan, a canal, Panama!". > > /^\W*(?:((.)\W*(?1)\W*\2|)|((.)\W*(?3)\W*\4|\W*.\W*))\W*$/i
It still doesn't work on "ababa" > > Hm, I see that *this* pattern also makes Perl 5.10 loop. > Using that pattern, with all instances of \W* removed, seems to work in > both Perl and PCRE: > > PCRE version 7.9 2009-04-11 > > /^(?:((.)(?1)\2|)|((.)(?3)\4|.))$/ This also does not work on "ababa". I have PCRE version 7.8 2008-09-05 -- ## List details at http://lists.exim.org/mailman/listinfo/pcre-dev
