Regex Roulette · #24 · 2026-04-28
Match valid snake_case identifiers
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
- hello_world — not yet evaluated
- my_var — not yet evaluated
- a_b_c — not yet evaluated
- test — not yet evaluated
Must not match
- Hello_World — not yet evaluated
- _leading — not yet evaluated
- trailing_ — not yet evaluated
- double__under — 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