caesar_cipher.rb

def caesar_cipher(string)
    data = string.split("")
    new = []
    data.each do |letter|
        if letter.ord > 122 or letter.ord < 65
            new << letter
        elsif letter == letter.upcase
            transform = (letter.ord + 13)
            transform -= 26 if transform > 90
            new << transform.chr
        elsif letter == letter.downcase
            transform = (letter.ord + 13)
            transform -= 26 if transform > 122
            new << transform.chr
         end
    end
    new.join("")
end