anansi wrote:
> I'll wait with my solution for a further hour ;) but a comment to your 
> solution:
> try out: ruby ccc.rb 5508 0412 3456 7893
> it should show: Diners Club US & Canada or Mastercard
> but shows just Mastercaards
Fixed, and resubmitting.  Thanks for the lookout.  I didn't include that 
initially because I didn't think there would be overlap.  I didn't even 
bother to look myself and see if that assumption was true.

# ccc.rb
# Checking Credit Cards

class String
  def begins_with?(str)
    temp = self.slice(0...str.length)
    temp == str
  end
end

class Array
  def collect_with_index
    self.each_with_index do |x, i|
      self[i] = yield(x, i)
    end
  end
end

class CCNumber
  #This data was taken from http://en.wikipedia.org/wiki/Credit_card_number
  TYPES = [
    Hash['type' => 'American Express',               'key' => [34, 
37],                     'length' => [15]],
    Hash['type' => 'China Union Pay',                 'key' => 
(622126..622925).to_a, 'length' => [16]],
    Hash['type' => 'Diners Club Carte Blanche', 'key' => 
(300..305).to_a,          'length' => [14]],
    Hash['type' => 'Diners Club International', 'key' => 
[36],                          'length' => [14]],
    Hash['type' => 'Diners Club US & Canada',    'key' => 
[55],                           'length' => [16]],
    Hash['type' => 'Discover',                            'key' => 
[6011, 65],                  'length' => [16]],
    Hash['type' => 'JCB',                                    'key' => 
[35],                           'length' => [16]],
    Hash['type' => 'JCB',                                    'key' => 
[1800, 2131],               'length' => [15]],
    Hash['type' => 'Maestro',                             'key' => 
[5020, 5038, 6759],        'length' => [16]],
    Hash['type' => 'MasterCard',                        'key' => 
(51..55).to_a,               'length' => [16]],
    Hash['type' => 'Solo',                                  'key' => 
[6334, 6767],                'length' => [16, 18, 19]],
    Hash['type' => 'Switch',                               'key' => 
[4903, 4905, 4911, 4936, 564182, 633110, 6333, 6759],
                                                                                                                        
'length' => [16, 18, 19]],
    Hash['type' => 'Visa',                                  'key' => 
[4],                             'length' => [13, 16]],
    Hash['type' => 'Visa Electron',                    'key' => [417500, 
4917, 4913],   'length' => [16]]
    ]
   
  #number should be an array of numbers as strings e.g. ["1", "2", "3"]
  def initialize(array)
    @number = array.collect{|num| num.to_i}
  end
 
  def type
    names = Array.new
    TYPES.each do |company|
      company['key'].each  do |key|
        if company['length'].include?(@number.length)  and 
@number.join.begins_with?(key.to_s)
          names << company['type']
        end
      end
    end
    names.empty? ? ["Unknown"] : names
  end
 
  def valid?
    temp = @number.reverse.collect_with_index{|num, index| index%2 == 0 
? num*2 : num}
    sum = temp.collect{|num|num > 9 ? [1, num%10] : 
num}.flatten.inject{|s, n| s+n}
    sum%10 == 0
  end
 
  def process
    puts "The card type is #{self.type.join(' or ')}"
    puts "The card number is #{self.valid? ?  'valid' : 'invalid'}"
  end
end

if $0 == __FILE__
  abort "You must enter a number!" if ARGV.empty?
  CCNumber.new(ARGV.join.strip.split(//)).process
end