Regular Expression Tester v1.0

Character Classes

• . - Any character except newline
• \d - Digit (0-9)
• \w - Word character (a-z, A-Z, 0-9, _)
• \s - Whitespace
• [abc] - Any of a, b, or c
• [^abc] - Not a, b, or c
• [a-z] - Character between a and z

Quantifiers

• * - 0 or more
• + - 1 or more
• ? - 0 or 1
• {3} - Exactly 3
• {3,} - 3 or more
• {3,5} - Between 3 and 5

Anchors & Boundaries

• ^ - Start of string/line
• $ - End of string/line
• \b - Word boundary
• \B - Not word boundary

Groups & Lookaround

• (abc) - Capturing group
• (?:abc) - Non-capturing group
• a|b - a or b
• (?=abc) - Positive lookahead
• (?!abc) - Negative lookahead

Flags

• g - Global (find all matches)
• m - Multiline
• i - Case insensitive