26hexiadecimal

gistfile1.rb

# Number <-> AZ

# 26 hexiadecimal  AZ -> Number
# ex. 'AA'.to_i26 => 27
class String
  def to_i26
    return nil unless self.to_s =~ /^[a-zA-Z]+$/
    self.upcase!
    str = ""
    n = 1
    #each char
    self.bytes do |s|
      #string initial need adjust
      aj = (self.to_s.size > 1 && n == 1)? 1 : 0  
      if s <= 74
        #A-J => 0-9
        str << (s - 65 + aj).to_s
      else
        #K-Z => A-Q
        str << (s - 10 + aj).chr
      end
      n += 1   
    end
    str.to_i(26) + 1
  end
end

# 26 hexiadecimal Number -> AZ
# ex. 28.to_i26 => 'AA'
class Integer
  def to_s26
    str=(self-1).to_s(26).upcase
    n=1
    re=""
    str.bytes do |s|
      #string initial need adjust
      aj = (str.size > 1 && n == 1)? 1 : 0  
      if s <= 57
        #0-9 => A-J
        re << (s + 17 - aj).chr
      else
        #A-Q => K-Z
        re << (s + 10 - aj).chr
      end
      n += 1   
    end
    re
  end
end