How to Find and Replace Text Using Regular Expressions
Regular expressions enable powerful pattern-based find and replace operations. Learn practical regex patterns for common text transformation tasks.
Key Takeaways
- Standard find-and-replace handles exact text matches.
- Capture groups `()` let you rearrange matched text.
- Lookahead `(?=...)` matches a position before a pattern without including it.
- Always test regex patterns on a small sample before applying to large text.
- ## Essential Patterns | Pattern | Matches | Example | |---------|---------|--------| | `\d{3}-\d{4}` | Phone numbers | 555-1234 | | `[\w.
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Beyond Simple Find and Replace
Standard find-and-replace handles exact text matches. Regular expressions match patterns — phone numbers, email addresses, dates, URLs — letting you transform text at scale with surgical precision.
Essential Patterns
| Pattern | Matches | Example |
|---|---|---|
\d{3}-\d{4} |
Phone numbers | 555-1234 |
[\w.]+@[\w.]+ |
Email addresses | [email protected] |
\d{1,2}/\d{1,2}/\d{4} |
Dates (M/D/YYYY) | 3/15/2025 |
https?://\S+ |
URLs | https://example.com/page |
Capture Groups for Transformation
Capture groups () let you rearrange matched text. For example, converting dates from MM/DD/YYYY to YYYY-MM-DD: pattern (\d{2})/(\d{2})/(\d{4}) with replacement $3-$1-$2.
Lookahead and Lookbehind
Lookahead (?=...) matches a position before a pattern without including it. Lookbehind (?<=...) matches a position after a pattern. These are powerful for inserting or removing text at specific locations.
Testing Regex Safely
Always test regex patterns on a small sample before applying to large text. Use tools that highlight matches in real-time so you can verify the pattern captures exactly what you intend.
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