Ruby implementation of the Luhn, Damm and Verhoeff check digit algorithms

• is the latest released version
• For the version under development (master), check version.rb

Add this line to your application's Gemfile:

gem 'check_digit'

And then execute:

$ bundle

Or install it yourself as:

$ gem install check_digit

Each implementation provides the same 2 class methods:

• checksum(num) - returns a new number with the checksum digit appended at the end
• valid?(num) - returns true if the number has a valid checksum digit, false if the number has an invalid checksum digit

Code sample:

require 'check_digit'

Damm.checksum(123) # returns 1234
Damm.valid?(1234) # returns true
Damm.valid?(1239) # returns false

Source: http://www.augustana.ab.ca/~mohrj/algorithms/checkdigit.html

* Not entirely sure if Luhn catches all phonetic errors, e.g. 13 instead of 30

#####Legend

1. Prevents all errors
2. Prevents most errors
3. Prevents some errors
4. Does not prevent any errors

#####50,000 iterations (time in seconds - higher is better)*

* Test was on Linux 14.04 with 2.80GHz Intel Xeon E5-1603 - relative timing is more important to consider when comparing performance

1. Fork it ( https://github.com/elitwin/check_digit/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

The Verhoeff implementation was provided from this repo (https://github.com/bai/verhoeff) and was the inspiration for the interface (checksum, valid?) used by all the implementations