Cheat sheets for RegExp
Cheat sheets for RegExp
#General
Basic Syntax
/.../ | Start and end regex delimiters |
| | Alternation |
() | Grouping |
Position Matching
^ | Start of string or start of line in multi-line mode |
\A | Start of string |
$ | End of string or end of line in multi-line mode |
\Z | End of string |
\b | Word boundary |
\B | Not word boundary |
\< | Start of word |
\> | End of word |
Character Classes
\s | Whitespace |
\S | Not whitespace |
\w | Word |
\W | Not word |
\d | Digit |
\D | Not digit |
\x | Hexadecimal digit |
\O | Octal digit |
Special Characters
\n | Newline |
\r | Carriage return |
\t | Tab |
\v | Vertical tab |
\f | Form feed |
\xxx | Octal character xxx |
\xhh | Hex character hh |
Groups and Ranges
. | Any character except newline (\n) |
(a|b) | a or b |
(…) | Group |
(?:…) | Passive (non-capturing) group |
[abc] | a, b or c |
[^abc] | Not a, b or c |
[a-z] | Letters from a to z |
[A-Z] | Uppercase letters from A to Z |
[0-9] | Digits from 0 to 9 |
Note: Ranges are inclusive.
Quantifiers
* | 0 or more |
+ | 1 or more |
? | 0 or 1 |
{3} | Exactly 3 |
{3,} | 3 or more |
{3,5} | 3, 4 or 5 |
Note: Quantifiers are greedy - they match as many times as possible. Add a ? after the quantifier to make it ungreedy.
Escape Sequences
\:Escape following character. Used to escape any of the following metacharacters: {}[]()^$.|*+?\. | |
\Q | Begin literal sequence |
\E | End literal sequence |
String Replacement
$1 | 1st group |
$2 | 2nd group |
$n | nth group |
| `$`` | Before matched string |
$' | After matched string |
$+ | Last matched string |
$& | Entire matched string |
Note: Some regex implementations use \ instead of $.
Assertions
?= | Lookahead assertion |
?! | Negative lookahead |
?<= | Lookbehind assertion |
?!=, ?<! | Negative lookbehind |
?> | Once-only subexpression |
?() | Condition if-then |
?()| | Condition if-then-else |
?# | Comment |
POSIX
[:upper:] | Uppercase letters |
[:lower:] | Lowercase letters |
[:alpha:] | All letters |
[:alnum:] | Digits and letters |
[:digit:] | Digits |
[:xdigit:] | Hexadecimal digits |
[:punct:] | Punctuation |
[:blank:] | Space and tab |
[:space:] | Blank characters |
[:cntrl:] | Control characters |
[:graph:] | Printed characters |
[:print:] | Printed characters and spaces |
[:word:] | Digits, letters and underscore |
Pattern Modifiers
g | Global match |
i | Case-insensitive |
m | Multi-line mode. Causes ^ and $ to also match the start/end of lines. |
s | Single-line mode. Causes . to match all, including line breaks. |
x | Allow comments and whitespace in pattern |
e | Evaluate replacement |
U | Ungreedy mode |