| 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 |
| \n |
The newline (line-feed) character |
| \r |
The carriage-return character |
| \f |
The form-feed character |
| \a |
The alert (bell) character |
| \e |
The escape character |
| \cX |
The control character corresponding to X |
|
| Characters 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] inclusive (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 characters 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] |
|
| Boundary matchers |
| ^ |
The beginning of a line |
| $ |
The end of a line |
| \b |
A word boundary |
| \B |
A non-word boundary |
| \A |
The beginning ot the input |
| \G |
The end of the previous match |
| \Z |
The end ot the input but for the final terminator, if any |
| \z |
The end ot 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,p} |
X, at least n times, but not more than p 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,p}? |
X, at least n times, but not more than p 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,p}+ |
X, at least n times, but not more than p 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 |
| (?=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 |