Regex Basics and Testing

Regular expressions (regex) are powerful patterns used for matching text. This guide covers the basics and how to test your patterns.

Basic Patterns

• . - Matches any single character
• * - Matches 0 or more of the preceding character
• + - Matches 1 or more of the preceding character
• ? - Matches 0 or 1 of the preceding character
• ^ - Matches the start of a string
• $ - Matches the end of a string

Character Classes

• [abc] - Matches any character in the set
• [^abc] - Matches any character NOT in the set
• \d - Matches any digit (0-9)
• \w - Matches any word character
• \s - Matches any whitespace

Common Flags

• g - Global: find all matches
• i - Case-insensitive matching
• m - Multiline mode

Testing Your Regex

Use our Regex Tester to:

1. Enter your regex pattern
2. Select appropriate flags
3. Add test text
4. See matches and capture groups highlighted