RegExp
Character classes
| Pattern |
Description |
. |
Any character, except newline |
\w |
Word |
\d |
Digit |
\s |
Whitespace |
\W |
Not word |
\D |
Not digit |
\S |
Not whitespace |
[abc] |
Any of a, b, or c |
[a-e] |
Characters between a and e |
[1-9] |
Digit between 1 and 9 |
[[:print:]] |
Any printable character including spaces |
[^abc] |
Any character except a, b or c |
Anchors
| Pattern |
Description |
\G |
Start of match |
^ |
Start of string * |
$ |
End of string * |
\A |
Start of string |
\Z |
End of string |
\z |
Absolute end of string |
\b |
A word boundary |
\B |
Non-word boundary |
^abc |
Start with abc |
abc$ |
End with abc |
For multiline patterns (m flag), ^ and $ will act as start and end of line.
Escaped characters
| Pattern |
Description |
\. \* \\ |
Escape special character used by regex |
\t |
Tab |
\n |
Newline |
\r |
Carriage return |
Groups
| Pattern |
Description |
(abc) |
Capture group |
(a|b) |
Match a or b |
(?:abc) |
Match abc, but don’t capture |
\1 |
Substituted with text matched of the 1st capturing group |
Quantifiers
| Pattern |
Description |
a* |
Match 0 or more |
a+ |
Match 1 or more |
a? |
Match 0 or 1 |
a{5} |
Match exactly 5 |
a{,3} |
Match up to 3 |
a{3,} |
Match 3 or more |
a{1,3} |
Match between 1 and 3 |
Lookahead & Lookbehind
| Pattern |
Description |
a(?=b) |
Match a in baby but not in bay |
a(?!b) |
Match a in Stan but not in Stab |
(?<=a)b |
Match b in crabs but not in cribs |
(?<!a)b |
Match b in fib but not in fab |
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