ton_chat

Try using my new non-KISS, très l33t solution to check any String for palindromosity.  I'm sure Matz should add this to 1.8.4.

#!/usr/bin/ruby

#extend Ruby's built-in String class to allow palindrome checking, then give it a try!
#public domain, november 25th, 2005 by dale anderson

class String
        def palindrome?
                #normalize the string, result: s
                s = self.gsub(/\W/, '').upcase

                #string length, half length
                sl = s.length
                hl = sl / 2

                # sl    hl      p1      p2      SAMPLE FIGURES
                # 8     4       0-3     4-7  
                # 7     3       0-2     4-6
                # 6     3       0-2     3-5
                # 5     2       0-1     3-4
                # 4     2       0-1     2-3
                # 3     1       0-0     2-2
                # 2     1       0-0     1-1
                # 1     0       0-0     0-0 *
                # 0     0       0-0     0-0 *

                # * we observe that 0 and 1 are special cases
                return true if sl <= 1

                #compare the p1 versus the backwards p2
                p1 = s[ 0       ..      (hl-1)  ]
                p2 = s[ (sl-hl) ..     (sl-1)    ]

                #puts " *** '#{p1}' vs. '#{p2}' ***"

                return true if p1 == p2.reverse
                return false
        end
end



tests = {
        'pull-up' => true,
        'Oo.pSpOo' => true,
        '' => true,
        'A' => true,
        '4321/abc\ba 1 2 3 4' => true,

        "hi there" => false,
        'mememe' => false
        }

for potpal,georgeboole in tests
        raise "Potential Palindrome: '#{potpal}' was #{not georgeboole}!" unless
                potpal.palindrome? == georgeboole
end

Thanks for the video.