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Regular Expressions: A Beginner-Friendly Guide

Learn the basics of regular expressions (regex) with practical examples. Master pattern matching for text processing and validation.

2025-01-086 min

What are Regular Expressions?

Regular expressions (regex) are patterns used to match character combinations in text. They're essential for text processing, validation, and search operations.

Basic Regex Syntax

Character Classes

  • . - Any character except newline
  • \d - Any digit (0-9)
  • \w - Word character (a-z, A-Z, 0-9, _)
  • \s - Whitespace character
  • Quantifiers

  • * - Zero or more
  • + - One or more
  • ? - Zero or one
  • {n} - Exactly n times
  • {n,m} - Between n and m times
  • Anchors

  • ^ - Start of string
  • $ - End of string
  • \b - Word boundary
  • Common Regex Patterns

    Email Validation

    ^[\w.-]+@[\w.-]+\.[a-zA-Z]{2,}$

    Phone Number

    ^\+?[1-9]\d{1,14}$

    URL Pattern

    ^https?://[\w.-]+\.[a-zA-Z]{2,}

    Tips for Writing Regex

  • Start simple and build complexity
  • Use online testers to verify patterns
  • Consider edge cases
  • Add comments for complex patterns
  • Test with various inputs
  • Our Regex Tester Features

  • Real-time matching
  • Match highlighting
  • Common pattern library
  • Regex explanation
  • Flag options (g, i, m)