Also known as a shift cipher, the Ceasar Cipher is one of the oldest and simplest encoding techniques. A Ceasar Cipher works by shifting the alphabet by a set number of letters down the alphabet. For example, with a left shift of 3, 'D' would be replaced by 'A', 'E' would be replaced by 'B', and so on. See below for a full alphabet example with a left shift of 3:
plain: ABCDEFGHIJKLMNOPQRSTUVWXYZ
cipher: XYZABCDEFGHIJKLMNOPQRSTUVW
Create a file named caesar_cipher.rb and within that file, write a program that will take any string, and encode it based on a shift value provided by the user. The interaction pattern for this program might look something like this:
cipher = CeasarCipher.new
cipher.encode("Hello World", 5)
=> "CZGGJ RJMGY"