luhncalc

luhncalc is a small crate that works both as a command-line utility and as a Rust library for validating digit sequences with the Luhn algorithm and calculating the next check digit.

Command line usage

Validate the following invalid digit sequence 1234567890:

> luhncalc 1234567890

Sequence:       1234567890
Valid sequence: false
Next digit:     3

Validate the following valid digit sequence 12345678903:

> luhncalc 12345678903

Sequence:       12345678903
Valid sequence: true
Next digit:     1

Library usage

Add the crate to your project:

[dependencies]
luhncalc = "1"

Use one of the public functions from Rust code:

use luhncalc::{analyze, calculate_check_digit, validate};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    assert_eq!(validate("12345678903")?, true);
    assert_eq!(calculate_check_digit("1234567890")?, '3');

    let analysis = analyze("12345678903")?;
    assert_eq!(analysis.valid, true);
    assert_eq!(analysis.next_check_digit, '1');

    Ok(())
}

The library returns an error when the digit sequence is empty or contains anything other than ASCII digits 0-9.

License

This project is licensed under either of

• the Apache License, Version 2.0
• the MIT license

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-20 license, shall be dual licensed as above, without any additional terms or conditions.