Regular expressions (regex) are powerful tools for pattern matching and text manipulation. Here's a quick guide to get started:

📌 Basic Concepts

  • Literal Characters: Match exact characters (e.g., a matches "a")
  • Special Characters: Use . to match any single character, * for zero or more repetitions
  • Character Classes: [abc] matches any one of "a", "b", or "c"
  • Anchors: ^ asserts the start of a line, $ asserts the end
Regex Pattern

🔍 Common Use Cases

  • Validation: Check email formats (^\w+@[a-zA-Z_]+?\.[a-zA-Z]{2,3}$)
  • Search & Replace: Replace all digits with # using \d in replacement
  • Splitting Text: Divide strings by whitespace with \s+
  • Extracting Data: Capture group matches using parentheses ()
Pattern Matching

✅ Example Code

import re
text = "The price is $123.45"
match = re.search(r'\$(\d+\.?\d*)', text)
print(match.group(1))  # Output: 123.45
Code Example

🚀 Advanced Tips

  • Lookaheads: Use (?=...) to assert a subpattern without consuming characters
  • Escaping: Escape special characters with \ (e.g., \. matches a literal dot)
  • Flags: Add re.IGNORECASE for case-insensitive matching
Advanced Tips

For deeper exploration, check our Regex Two guide on complex patterns and performance optimization.