Regular Expression Quick Reference

Shorthand

\d

Any decimal digit.

\D

Any character that is not a digit.

\w

Word character, letters digits and underscore.

\W

Any character that is not a word character.

\s

Whitespace including space tab and newline.

\S

Any character that is not whitespace.

.

Any character except newline unless the dotall flag is set.

Bracket expressions

[abc]

Any one of a, b or c.

[^abc]

Any character other than a, b or c.

[a-z]

Any character in the range a to z.

[[:alpha:]]

POSIX class for alphabetic characters.

[[:xdigit:]]

POSIX class for hexadecimal digits.

Flags

i

Case insensitive matching.

m

Multiline, anchors match at line breaks.

s

Dotall, the dot also matches newline.

x

Extended, ignore unescaped whitespace.