| Construct | Matches |
| Characters |
| x |
The character x |
| \\ |
The backslash character |
| \0n |
The character with octal value 0n
(0 <= n <= 7) |
| \0nn |
The character with octal value 0nn
(0 <= n <= 7) |
| \0mnn |
The character with octal value 0mnn
(0 <= m <= 3,
0 <= n <= 7) |
| \xhh |
The character with
hexadecimal value 0xhh |
| \uhhhh |
The character with
hexadecimal value 0xhhhh |
| \t |
The tab character ('\u0009') |
| \n |
The newline (line feed) character
('\u000A') |
| \r |
The carriage-return character
('\u000D') |
| \f |
The form-feed character ('\u000C') |
| \a |
The alert (bell) character ('\u0007') |
| \e |
The escape character ('\u001B') |
| \cx |
The control character corresponding to x |
| |
| 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 for b
and c: [ad-z] (subtraction) |
| [a-z&&[^m-p]] |
a through z, and not m
through p: [a-lq-z](subtraction) |
| |
| Predefined character classes |
| . |
Any character |
| \d |
A digit: [0-9] |
| \D |
A non-digit: [^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] |
| |
| POSIX character classes (US-ASCII
only) |
| \p{Lower} |
A lower-case alphabetic character:
[a-z] |
| \p{Upper} |
An upper-case alphabetic
character:[A-Z] |
| \p{ASCII} |
All ASCII:[\x00-\x7F] |
| \p{Alpha} |
An alphabetic
character:[\p{Lower}\p{Upper}] |
| \p{Digit} |
A decimal digit: [0-9] |
| \p{Alnum} |
An alphanumeric
character:[\p{Alpha}\p{Digit}] |
| \p{Punct} |
Punctuation: One of
!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~ |
| \p{Graph} |
A visible character:
[\p{Alnum}\p{Punct}] |
| \p{Print} |
A printable character: [\p{Graph}] |
| \p{Blank} |
A space or a tab: [ \t] |
| \p{Cntrl} |
A control character: [\x00-\x1F\x7F] |
| \p{XDigit} |
A hexadecimal digit: [0-9a-fA-F] |
| \p{Space} |
A whitespace character: [ \t\n\x0B\f\r] |
| |
| Classes for Unicode blocks and categories |
| \p{InGreek} |
A character in the Greek block (simple
block) |
| \p{Lu} |
An uppercase letter (simple category) |
| \p{Sc} |
A currency symbol |
| \P{InGreek} |
Any character except one in the Greek block
(negation) |
| [\p{L}&&[^\p{Lu}]] |
Any letter except an uppercase letter
(subtraction) |
| |
| Boundary matchers |
| ^ |
The beginning of a line |
| $ |
The end of a line |
| \b |
A word boundary |
| \B |
A non-word boundary |
| \A |
The beginning of the input |
| \G |
The end of the previous match |
| \Z |
The end of the input but for the final terminator,
if any |
| \z |
The end of the input |
| |
| Greedy quantifiers |
| X? |
X, once or not at all |
| X* |
X, zero or more times |
| X+ |
X, one or more times |
| X{n} |
X, exactly n times |
| X{n,} |
X, at least n times |
| X{n,m} |
X, at least n but not more than m
times |
| |
| Reluctant quantifiers |
| X?? |
X, once or not at all |
| X*? |
X, zero or more times |
| X+? |
X, one or more times |
| X{n}? |
X, exactly n times |
| X{n,}? |
X, at least n times |
| X{n,m}? |
X, at least n but not more than m
times |
| |
| Possessive quantifiers |
| X?+ |
X, once or not at all |
| X*+ |
X, zero or more times |
| X++ |
X, one or more times |
| X{n}+ |
X, exactly n times |
| X{n,}+ |
X, at least n times |
| X{n,m}+ |
X, at least n but not more than m
times |
| |
| Logical operators |
| XY |
X followed by Y |
| X|Y |
Either X or Y |
| (X) |
X, as a capturing group |
| |
| Back references |
| \n |
Whatever the nth
capturing group matched |
| |
| Quotation |
| \ |
Nothing, but quotes the following character |
| \Q |
Nothing, but quotes all characters until
\E |
| \E |
Nothing, but ends quoting started by \Q |
| |
| Special constructs (non-capturing) |
| (?:X) |
X, as a non-capturing group |
| (?idmsux-idmsux) |
Nothing, but turns match flags on - off |
| (?idmsux-idmsux:X) |
X, as a non-capturing group with the given
flags on - off |
| (?=X) |
X, via zero-width positive lookahead |
| (?!X) |
X, via zero-width negative lookahead |
| (?<=X) |
X, via zero-width positive lookbehind |
| (?<!X) |
X, via zero-width negative lookbehind |
| (?>X) |
X, as an independent, non-capturing
group |
