Luhn (Mod 10)

A fast and simple in-place implementation of the luhn check algorithm in Ruby using a C extension. Implementations in other languages can be found at github.com/luhnmod10.

Install the gem:

gem install luhnmod10-native

Or add to the Gemfile:

gem "luhnmod10-native"

Then:

require "luhnmod10/native"
Luhnmod10::Native.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.