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Regex Pattern Builder

Generates a regex pattern with detailed explanations, test cases, variations, and implementation code for your specific matching requirements.

When to use this prompt

You need a regular expression for a specific validation or extraction task but want more than just the pattern itself. This template is useful when you need to understand how the regex works, see it tested against edge cases, and get ready-to-use code examples.

You are a regex expert who creates precise patterns.

Create a regex pattern for [USE CASE].

Requirements:
- Should match: [EXAMPLES]
- Should NOT match: [COUNTER-EXAMPLES]
- Language/engine: [LANGUAGE]

Provide:
1. Regex pattern with explanation
   - Pattern breakdown piece by piece
   - What each part does

2. Test cases
   - Valid matches (10+)
   - Invalid non-matches (10+)
   - Edge cases

3. Common variations
   - Stricter version
   - Looser version
   - With capture groups

4. Implementation examples
   - How to use in code
   - Validation function
   - Extraction function

5. Performance notes
   - Backtracking risks
   - Optimization tips
   - Alternative approaches

Also explain common mistakes people make with this type of pattern.

Free to use — the optimizer tailors this template to your exact task and target AI.

How to customize it

  • [USE CASE] — Describe what you're trying to match, such as 'email addresses', 'phone numbers in international format', or 'hexadecimal color codes'
  • [EXAMPLES] — List actual strings that should successfully match your pattern, providing concrete positive test cases
  • [COUNTER-EXAMPLES] — Provide strings that look similar but should NOT match, helping the AI understand boundaries and exclusions
  • [LANGUAGE] — Specify the regex engine or programming language (Python, JavaScript, Java, PCRE, etc.) since syntax and features vary

What you'll get back

The AI returns a complete regex solution including the pattern itself with piece-by-piece breakdown, at least 10 valid and 10 invalid test cases plus edge cases, three pattern variations (stricter, looser, and with capture groups), code examples showing validation and extraction functions, performance considerations about backtracking and optimization, and common pitfalls for that pattern type.

regexpatternsvalidation

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Make this prompt yours

PromptWizz rewrites this template around your specific task, audience, and target AI — and shows you why each change works.

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    llms.txt