Re: Palindrome Program without Reverse function

my $palindrome_re = qr{
    \b
    (?<pal>          # A palindrome is a sandwich...
        (?<char>\w)  # starting with white bread...
        (?:          # filled with either...
            \w?      #   peanut butter (maybe)...
        |            # or...
            (?&pal)  #   another sandwich...
        )
        \k<char>     # topped off with white bread!
    )
    \b
}x;

@ARGV = 'words';
/$palindrome_re/ and print while <>;
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Comment on Re: Palindrome Program without Reverse function Download Code

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Re^2: Palindrome Program without Reverse function by BrowserUk (Patriarch) on Oct 31, 2011 at 05:02 UTC
Clever, but slow: `sub isPalindrome{ substr( $_[0], $_, 1 ) eq substr( $_[0], -($_+1), 1 ) or return for 0 .. length( $_[0] ) >> 1; 1; }` [download] With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]
Re^2: Palindrome Program without Reverse function by ww (Archbishop) on Oct 31, 2011 at 13:49 UTC
...Liked the regex; not so much, lines 15 and 16... so tried 5.012 which didn't like 16 either. So left the regex alone and re-wrote Lines 15-16 (much more verbosely) to work nicely with 5.12: `#!/usr/bin/perl use Modern::Perl; # 934820 my $palindrome_re = qr{ \b (?<pal> # A palindrome is a sandwich... (?<char>\w) # starting with white bread... (?: # filled with either... \w? # peanut butter (maybe)... \| # or... (?&pal) # another sandwich... ) \k<char> # topped off with white bread! ) \b }ix; my @Rev_arr = qw /Research tattarrattat Kanakanak Qaanaaq Foobarblivit +z/; for my $word(@Rev_arr) { if ($word =~ /$palindrome_re/) { say $word; } else { say "$word is NOT a palindrome"; } }` [download] Execution: `C:\>934820.pl Research is NOT a palindrome tattarrattat Kanakanak Qaanaaq Foobarblivitz is NOT a palindrome C:\>` [download]	[reply] [d/l] [select]