Regular Expression Guide 📘

Regular expressions (regex) are powerful tools for pattern matching and text manipulation. Here's a concise overview to help you master them:

🧮 Basics of Regex Syntax

• Literal Characters: Match exact characters (e.g., a matches "a")
• Special Characters:
  • . - Matches any single character (except newline)
  • * - Matches 0 or more of the preceding element
  • + - Matches 1 or more of the preceding element
  • ? - Matches 0 or 1 of the preceding element
• Anchors:
  • ^ - Start of a string
  • $ - End of a string
• Grouping: Use parentheses () to create subpatterns

🔍 Common Regex Patterns

• Email Validation:

  ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$
  

• URL Matching:

  ^(https?:\/\/)?[^\s/$.?#].[^\s]*$
  

• Date Formats:
  • ^\d{4}-\d{2}-\d{2}$ for YYYY-MM-DD
  • ^\d{2}\/\d{2}\/\d{4}$ for DD/MM/YYYY

💡 Practical Tips

1. Test Incrementally: Start with simple patterns and build complexity.
2. Use Tools: Try online testers like Regex101 or IDE plugins.
3. Escape Special Characters: Use \ to treat symbols like . or * as literals.

For deeper exploration, check our Regex Advanced Guide 🌐.