Regex Roulette · #32 · 2026-05-06
Match strings formatted like credit card numbers (4 groups of 4 digits)
Difficulty 2/3
How to play
Write a regex that matches all green strings and rejects all red strings. Live feedback shows which strings pass. Shorter patterns score better.
Must match
- 1234-5678-9012-3456 — not yet evaluated
- 0000-0000-0000-0000 — not yet evaluated
- 9999-9999-9999-9999 — not yet evaluated
Must not match
- 1234567890123456 — not yet evaluated
- 1234-5678-9012 — not yet evaluated
- 1234-5678-9012-345 — not yet evaluated
- abcd-efgh-ijkl-mnop — not yet evaluated
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Pattern body only — slashes and flags (e.g. /g, /i) aren't part of the input.
0/200 chars
Type a regex that matches all green strings and rejects all red strings · Back to hub