The article explores whether a regular expression can fully validate credit‑card numbers by incorporating the Luhn checksum. It explains the ISO card format, models the Luhn algorithm as a deterministic finite automaton, and provides a Python implementation of a regex that accepts only numbers passing the checksum.
Background
Credit‑card validation is usually performed with procedural code that computes the Luhn checksum; using a pure regex is considered unconventional.
- Source
- Lobsters
- Published
- Sep 13, 2026 at 09:39 PM
- Score
- 6.0 / 10