Regex Generator From Sample
Generate a regular expression from a sample string automatically.
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What is a regex generator?
Paste one sample of the format you care about and get a pattern that matches its shape: AB-1234 becomes [A-Z]{2}-\d{4}, lowercase runs become [a-z]{n}, and everything else is escaped literally. Optional anchors pin the match to the whole string, and a /pattern/g wrapper readies it for JavaScript. Expect a solid draft, not a finished validator.
How to use the Regex Generator
- 1 Paste one representative sample, such as an order code.
- 2 Review the generated pattern with its classes and {n} counts.
- 3 Toggle anchors or the /pattern/g wrapper to fit your code.
- 4 Copy the draft regex and loosen it against real data.
What you can use it for
- Getting a first draft pattern for a known format.
- Seeing how a string maps to character classes.
- Speeding up writing a validation regex.
- Producing a pattern for codes like SKUs or refs.
Frequently asked questions
What rules turn my sample into a pattern?
Consecutive characters of the same kind collapse into a class with a count: lowercase runs become [a-z]{n}, uppercase [A-Z]{n}, digits \d{n}, and punctuation is escaped as-is.
Should I ship the generated regex unchanged?
Rarely. One sample cannot show every variation your data allows, so widen counts or classes where real inputs differ, then confirm with the tester.
What do the anchor and wrapper toggles change?
Anchors add ^ and $ so only a full-string match passes. The wrapper prints /pattern/g literal syntax you can paste into JavaScript without extra quoting.
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