Quick reference

Special characters definitions

\   Quotes the next meta character

^   Match the beginning of a line

.   Match any character (except newline character)

$   Match the end of a line

|   Alternation

()  Group

[]  Character class

*      Match 0 or more times

+      Match 1 or more times

?      Match 0 or 1 times

{n}    Match exactly n times

{n,}   Match at least n times

{n,m}  Match at least n but no more than m times

Character classes

[abc]          a, b, or c (simple class)

[^abc]         Any character except a, b, or c (negation)

[a-zA-Z]       a through z, or A through Z, inclusive (range)

[a-d[m-p]]     a through d, or m through p: [a-dm-p] (union)

[a-z&&[def]]   d, e, or f (intersection)

[a-z&&[^bc]]   a through z, except b and c: [ad-z] (subtraction)

[a-z&&[^m-p]]  a through z, but excluding m through p: [a-lq-z] (subtraction)

Pre-defined character classes

.    Any character (except newline character)

\d   A digit character: [0-9]

\D   A non-digit character: [^0-9]

\s   A whitespace character: [ \t\n\x0B\f\r]

\S   A non-whitespace character: [^\s]

\w   A word character: [a-zA-Z_0-9]

\W   A non-word character: [^\w]