| Construct |
Matches |
| |
|---|
| Characters |
|---|
| x |
The character x |
| \ |
The backslash character |
| n |
The character with octal value 0n
(0 <= n <= 7) |
| nn |
The character with octal value 0nn
(0 <= n <= 7) |
| mnn |
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 |
| |
The tab character ('\u0009') |
|
|
The newline (line feed) character ('\u000A') |
|
|
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 (may or may not match line terminators) |
| d |
A digit: [0-9] |
| D |
A non-digit: [^0-9] |
| s |
A whitespace character: [
x0Bf
] |
| 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: [ ] |
| p{Cntrl} |
A control character: [x00-x1Fx7F] |
| p{XDigit} |
A hexadecimal digit: [0-9a-fA-F] |
| p{Space} |
A whitespace character: [
x0Bf
] |
| |
|---|
| 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 |
|
A word boundary |
| B |
A non-word boundary |
| A |
The beginning of the input |
| G |
The end of the previous match |
|
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 |
| |
|---|
| Grouping operators |
|---|
| (X) |
X. This capturing group is remembered so it can be referenced later. Numbered starting at 1. |
| (?:X) |
X. Used purely for grouping, and isn't remembered. |
| |
|---|
| 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 (all groupings are non-capturing) |
|---|
| (?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 |
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