RegEx Cheatsheet

regex.md

RegEx Cheatsheet

Contents:

1. Special characters
2. Quantifiers
3. Special sequences
4. Useful examples

Special characters

• \ - escapes special characters
• . - matches any character
• ^ - matches start of the string (or line if MULTILINE)
• $ - matches end of the string (or line if MULTILINE)
• [5b-d] - matches any chars '5', 'b', 'c' or 'd'
• [^a-c6] - matches any char except 'a', 'b', 'c' or '6'
• R|S- matches either regex R or regex S
• () - creates a capture group, and indicates precedence

Quantifiers

• * - 0 or more
• + - 1 or more
• ? - 0 or 1
• {m} - exactly 'm'
• {m,n} - from m to n (m defaults to 0, n to infinity)
• {m,n}? - from m to n, as few as possible

Special sequences

• \A - Start of string
• \b - Matches empty string at word boundary (between \w and \W)
• \B - Matches empty string not at word boundary
• \d - Digit
• \D - Non-digit
• \s - Whitespace: [ \t\n\r\f\v], more if LOCALE or UNICODE
• \S - Non-whitespace
• \w - Alphanumeric: [0-9a-zA-Z_], or is LOCALE dependant
• \W - Non-alphanumeric
• \Z - End of string

Useful examples

Find foo word:

\bfoo\b

Find a sequence of foo + some characters + bar:

\bfoo\b.*\bbarb\