Welcome to the Regular Expression (Regex) Reference Guide! This page serves as a comprehensive resource for understanding and utilizing regex patterns in your projects. Whether you're validating forms, parsing text, or searching for data, regex is an essential tool.

🔍 Core Regex Concepts

1. Basic Syntax

  • Regex uses special characters and literal characters to define patterns.
  • Anchors like ^ (start of string) and $ (end of string) ensure precise matching.
  • Quantifiers such as * (zero or more), + (one or more), and ? (zero or one) control repetition.

2. Character Classes

  • Use [abc] to match any single character in the set.
  • Ranges like [a-z] or [0-9] simplify matching sequences.
  • Special sequences such as \d (digits) or \w (word characters) are shorthand for common classes.

3. Metacharacters

  • Characters like ., *, ?, and () have special meanings.
  • Escaping with \ allows literal interpretation of metacharacters.

4. Groups & Captures

  • Parentheses () group subpatterns for reuse or extraction.
  • Backreferences like \1 match captured groups in the same regex.

🧠 Practical Examples

  • Email validation: 
    ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$
  • Phone number matching: 
    \+?1?[-. ]?\d{3}[-. ]?\d{3}[-. ]?\d{4}
  • Date format: 
    \d{4}-\d{2}-\d{2}|\d{2}/\d{2}/\d{4}

🌐 Expand Your Knowledge

For a deeper dive into regex applications, check out our Regex Tutorial or explore Regex Use Cases to see how patterns solve real-world problems.

regex_pattern
metacharacters

Let me know if you'd like to explore specific regex features or need help crafting a pattern for your use case! 🛠️