55502f40dc8b7c769880b10874abc9d0

A Caesar Cipher, or Caesar Shift, is a simple encryption method which substitutes the letter based on a fixed number movement. An example:

if the shift is set at 1,
than
caesar("ABCDEF",1) #=> "BCDEFG"

def caesar(text,shift)
count = 0
decoded = ''
while(count<text.size)
  decoded << (text[count]+shift).chr
  count += 1
end
decoded
end

Refactorings

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Aedd89a10aba3a46576ea4f604146c65

Carl Porth

August 9, 2008, August 09, 2008 06:49, permalink

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I've always seen shifts done with the unix tr command. You can do the same in ruby. Additionally this method handles the rotation of chars like

caesar("ABCDEF",22) #=> "WXYZAB"

def caesar(text,n)
  alpha = ('A'..'Z').to_a
  n.times { alpha.push(alpha.shift) }
  text.tr('A-Z', alpha.join)
end
Be1e3ee645d23c95ba650c21bc885927

Fabien Jakimowicz

August 9, 2008, August 09, 2008 11:34, permalink

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def caesar(text, shift)
  text.split('').collect {|letter| (letter[0] + shift).chr}.join
end
1e8f141e7857d397d8020ed3b759e88a

Maciej Piechotka

August 10, 2008, August 10, 2008 18:43, permalink

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Modification of Fabien Jakimowicz's code

def caesar(text, shift)
  text.split('').collect! {|letter| (letter[0] + shift).chr}.join
end
9e36aeb20f1b4a763043d3ce4942b454

Jonas Elfström

September 10, 2009, September 10, 2009 12:32, permalink

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Handles negative offsets.

def caesar(text,shift)
  shift = shift<0 ? 26-shift%26 : shift%26
  ab=('a'..'z').to_a*2
  text.downcase.tr('a-z', ab[shift..shift+26].join)
end
C9e9f08bc5cc53f053741a07b2fa9dd9

Neld

April 4, 2011, April 04, 2011 18:10, permalink

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asd

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