Regex Cheat Sheet | OverAPI.com

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Anchors

Anchros

^
Start of string, or start of line in multi-line pattern
\A
Start of string
$
End of string, or end of line in multi-line pattern
\Z
End of string
\b
Word boundary
\B
Not word boundary
\<
Start of word
\>
End of word

Quantifiers

Quantifiers

*
0 or more
+
1 or more
?
0 or 1
{3}
Exactly 3
{3,}
3 or more
{3,5}
3, 4 or 5
{,5}
5 or less

Character

Character Classes

\c
Control character
\s
White space
\S
Not white space
\d
Digit
\D
Not digit
\w
Word
\W
Not word
\x
Hexade-cimal digit
\O
Octal digit

Special

\n
New line
\r
Carriage return
\t
Tab
\v
Vertical tab
\f
Form feed
\xxx
Octal character xxx
\xhh
Hex character hh

Examples

Metacharacter

^abc
abc, abcdefg, abc123, ...
abc$
abc, endsinabc, 123abc, ...
a.c
abc, aac, acc, adc, aec, ...
bill|ted
ted, bill
ab{2}c
abbc
a[bB]c
abc, aBc
(abc){2}
abcabc
ab*c
ac, abc, abbc, abbbc, ...
ab+c
abc, abbc, abbbc, ...
ab?c
ac, abc
a\sc
a c

Sample

([A-Za-z0-9-]+)
Letters, numbers and hyphens
(\d{1,2}\/\d{1,2}\/\d{4})
Date (e.g. 21/3/2006)
([^\s]+(?=\.(jpg|gif|png))\.2円)
jpg, gif or png image
(^[1-9]{1}$|^[1-4]{1}[0-9]{1}$|^50$)
Any number from 1 to 50 inclusive
(#?([A-Fa-f0-9]){3}(([A-Fa-f0-9]){3})?)
Valid hexadecimal colour code
((?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,15})
8 to 15 character string with at least one upper case letter, one lower case letter, and one digit (useful for passwords).
(\w+@[a-zA-Z_]+?\.[a-zA-Z]{2,6})
Email addresses
(\<(/?[^\>]+)\>)
HTML Tag

POSIX

POSIX

[:upper:]
Upper case letters
[:lower:]
Lower case letters
[:alpha:]
All letters
[:alnum:]
Digits and letters
[:digit:]
Digits
[:xdigit:]
Hexade-cimal digits
[:punct:]
Punctu-ation
[:blank:]
Space and tab
[:space:]
Blank characters
[:cntrl:]
Control characters
[:graph:]
Printed characters
[:print:]
Printed characters and spaces
[:word:]
Digits, letters and underscore

Groups

Groups and Ranges

.
Any character except new line (\n)
(a|b)
a or b
(...)
Group
(?:...)
Passive (non-c-apt-uring) group
[abc]
Range (a or b or c)
[^abc]
Not a or b or c
[a-q]
Letter from a to q
[A-Q]
Upper case letter from A to Q
[0-7]
Digit from 0 to 7
\n
nth group/-sub-pattern

Modifiers

Modifiers

g
Global match
i
Case-i-nse-nsitive
m
Multiple lines
s
Treat string as single line
x
Allow comments and white space in pattern
e
Evaluate replac-ement
U
Ungreedy pattern

String

Replacement

$n
nth non-pa-ssive group
2ドル
"-xyz-" in /^(abc-(xy-z))$/
1ドル
"-xyz-" in /^(?:a-bc)-(xyz)$/
$`
Before matched string
$'
After matched string
$+
Last matched string
$&
Entire matched string

Assertions

Assertions

?=
Lookahead assertion
?!
Negative lookahead
?<=
Lookbehind assertion
?!= or ?<!
Negative lookbehind
?>
Once-only Subexp-ression
?()
Condition [if then]
?()|
Condition [if then else]
?#
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