Regex Guide

A quick reference guide to common regex characters

Regex Search Modifiers

|
or
marks an alternative acceptable text
```
/(?:sample)|(?:other)/
```
{3}
occurs
requires text to repeat specified amount of times
```
/(?:sample){5}/
```
{3,}
occurs at least
requires text to repeat at least the specified amount of times
```
/(?:sample){5, }/
```
{3, 6}
occurs between
requires text to repeat between the minimum and max range specified
```
/(?:sample){5, 8}/
```
+
one or more (greedy)
Marks text as occuring once or more, using a greedy search
```
/(?:sample)+/
```
+?
one or more (lazy)
Marks text as occuring once or more, using a lazy search
```
/(?:sample)+?/
```
*
zero or more (greedy)
Marks text as occuring zero or more times, using a greedy search
```
/(?:sample)*/
```
*?
zero or more (lazy)
Marks text as occuring zero or more times, using a lazy search
```
/(?:sample)*?/
```
(?=...)
followed by
requires search text to be followed by specified text
```
/sample(?=after)/
```
(?!...)
not followed by
requires search text to NOT be followed by specified text
```
/sample(?!after)/
```
(?<=...)
preceded by
requires search text to be preceded by specified text
```
/(?<=pre)sample/
```
(?<!...)
not preceded by
requires search text to NOT be preceded by specified text
```
/(?<!pre)sample/
```
^
at start
marks text as occuring at beginning
```
/^(?:sample)/
```
$
at end
marks text as occuring at end
```
/(?:sample)$/
```
?
optional
marks text as optional
```
/(?:sample)?/
```
(...)
captured
encapsulates text as a group and captures when matching
```
/(sample)/
```
(?:...)non-capture grouping
encapsulates text as a group without capturing
```
/(?:sample)/
```
(?<...>...) ... \k<...>
variable
uses a named capture group to match each \k<...> to the first instance
```
/(?<var>)\d{2}) and \k<var>/
```

Symbol	Name	Description	Example
\|	or	marks an alternative acceptable text	(?:sample)\|(?:other)
{3}	occurs	requires text to repeat specified amount of times	(?:sample){5}
{3,}	occurs at least	requires text to repeat at least the specified amount of times	(?:sample){5, }
{3, 6}	occurs between	requires text to repeat between the minimum and max range specified	(?:sample){5, 8}
+	one or more (greedy)	Marks text as occuring once or more, using a greedy search	(?:sample)+
+?	one or more (lazy)	Marks text as occuring once or more, using a lazy search	(?:sample)+?
*	zero or more (greedy)	Marks text as occuring zero or more times, using a greedy search	(?:sample)*
*?	zero or more (lazy)	Marks text as occuring zero or more times, using a lazy search	(?:sample)*?
(?=...)	followed by	requires search text to be followed by specified text	sample(?=after)
(?!...)	not followed by	requires search text to NOT be followed by specified text	sample(?!after)
(?<=...)	preceded by	requires search text to be preceded by specified text	(?<=pre)sample
(?<!...)	not preceded by	requires search text to NOT be preceded by specified text	(?<!pre)sample
^	at start	marks text as occuring at beginning	^(?:sample)
$	at end	marks text as occuring at end	(?:sample)$
?	optional	marks text as optional	(?:sample)?
(...)	captured	encapsulates text as a group and captures when matching	(sample)
(?:...)	non-capture grouping	encapsulates text as a group without capturing	(?:sample)
(?<...>...) ... \k<...>	variable	uses a named capture group to match each \k<...> to the first instance	(?<var>)\d{2}) and \k<var>

Special Characters

.
any character
matches any single character
[^...]
any character except
matches any single character not listed between [^ and ]
\d
any digit
matches any single digit
\Dnon-digit
matches any single character that is not a digit
\w
any letter
matches any single letter
\Wnon-letter
matches any single character that is not a letter
\sspace
matches a space between characters such as " "
\b
word boundary
marks a text as having a boundary, such as a space or start of the text

Symbol	Name	Description
.	any character	matches any single character
[^...]	any character except	matches any single character not listed between [^ and ]
\d	any digit	matches any single digit
\D	non-digit	matches any single character that is not a digit
\w	any letter	matches any single letter
\W	non-letter	matches any single character that is not a letter
\s	space	matches a space between characters such as " "
\b	word boundary	marks a text as having a boundary, such as a space or start of the text