This is a draft cheat sheet. It is a work in progress and is not finished yet.
Anchors
^ |
Start of line |
$ |
End of line |
\b |
Word boundary |
\B |
Not word boundary |
Special Character
\c |
Control Character |
\x |
Hexadecimal |
\O |
Octal |
\n |
Newline (OS neutral) |
\r |
Carriage Return |
\t |
Tab |
\f |
Form Feed |
\Q |
Begin literal sequence |
\E |
End literal Sequence |
Assertions
?= |
Positive Lookahead |
?! |
Negative Lookahead |
?<= |
Positive Lookbehind |
?!= or ?<! |
Negative Lookbehind |
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Quantifiers
* |
0 or more |
{3} |
Exactly 3 |
+ |
1 or more |
{3,} |
3 or more |
? |
0 or 1 |
{3,5} |
3, 4, or 5 |
Add a ? to a quantifier to make it ungreedy
Character Classes
\s |
[ \t\n\r\f] |
Whitespace |
\S |
[^ \t\n\r\f] |
Not whitespace |
\d |
[0-9] |
Digit |
\D |
[^0-9] |
Not digit |
\w |
[a-zA-Z0-9_] |
Word |
\W |
[^a-zA-Z0-9_] |
Not word |
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Metacharacters
. |
Match any one character (except \n) |
| |
Alteration OR |
( ) |
Group and Capture |
[ ] |
Define character class |
\ |
Escape next character |
Groups and Ranges
(a|b) |
a or b |
[abc] |
Range (a or b or c) |
[^abc] |
Not (a or b or c) |
[a-z] |
Lower case alphachar |
[a-z,A-Z] |
Case-insensitive alphachar |
[0-9,a-f,A-F] |
Hexadecimal range |
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