A fast and simple in-place implementation of the luhn check algorithm in Ruby. Implementations in other languages can be found at github.com/luhnmod10.
Install the gem:
gem install luhnmod10
Or add to the Gemfile:
gem "luhnmod10"Then:
require "luhnmod10"
Luhnmod10.valid?("4242424242424242")Contributions are welcome! If you can improve the execution time of this implementation without increasing its complexity, please open a pull request. To test your change, run make in the repository to run the tests and the benchmarks.