Quick-Start: Regex Cheat Sheet

The tables below are a reference to basic regex. While reading the rest of the site, when in doubt, you can always come back and look here. (It you want a bookmark, here's a direct link to the regex reference tables). I encourage you to print the tables so you have a cheat sheet on your desk for quick reference.

The tables are not exhaustive, for two reasons. First, every regex flavor is different, and I didn't want to crowd the page with overly exotic syntax. For a full reference to the particular regex flavors you'll be using, it's always best to go straight to the source. In fact, for some regex engines (such as Perl, PCRE, Java and .NET) you may want to check once a year, as their creators often introduce new features.

The other reason the tables are not exhaustive is that I wanted them to serve as a quick introduction to regex. If you are a complete beginner, you should get a firm grasp of basic regex syntax just by reading the examples in the tables. I tried to introduce features in a logical order and to keep out oddities that I've never seen in actual use, such as the "bell character". With these tables as a jumping board, you will be able to advance to mastery by exploring the other pages on the site.

How to use the tables

The tables are meant to serve as an accelerated regex course, and they are meant to be read slowly, one line at a time. On each line, in the leftmost column, you will find a new element of regex syntax. The next column, "Legend", explains what the element means (or encodes) in the regex syntax. The next two columns work hand in hand: the "Example" column gives a valid regular expression that uses the element, and the "Sample Match" column presents a text string that could be matched by the regular expression.

You can read the tables online, of course, but if you suffer from even the mildest case of online-ADD (attention deficit disorder), like most of us… Well then, I highly recommend you print them out. You'll be able to study them slowly, and to use them as a cheat sheet later, when you are reading the rest of the site or experimenting with your own regular expressions.

Enjoy!

If you overdose, make sure not to miss the next page, which comes back down to Earth and talks about some really cool stuff: The 1001 ways to use Regex.

Regex Accelerated Course and Cheat Sheet

For easy navigation, here are some jumping points to various sections of the page:

✽ Characters
✽ Quantifiers
✽ More Characters
✽ Logic
✽ More White-Space
✽ More Quantifiers
✽ Character Classes
✽ Anchors and Boundaries
✽ POSIX Classes
✽ Inline Modifiers
✽ Lookarounds
✽ Character Class Operations
✽ Other Syntax

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Characters

Character	Legend	Example	Sample Match
\d	Most engines: one digit from 0 to 9	file_\d\d	file_25
\d	.NET, Python 3: one Unicode digit in any script	file_\d\d	file_9੩
\w	Most engines: "word character": ASCII letter, digit or underscore	\w-\w\w\w	A-b_1
\w	.Python 3: "word character": Unicode letter, ideogram, digit, or underscore	\w-\w\w\w	字-ま_۳
\w	.NET: "word character": Unicode letter, ideogram, digit, or connector	\w-\w\w\w	字-ま‿۳
\s	Most engines: "whitespace character": space, tab, newline, carriage return, vertical tab	a\sb\sc	a b c
\s	.NET, Python 3, JavaScript: "whitespace character": any Unicode separator	a\sb\sc	a b c
\D	One character that is not a digit as defined by your engine's \d	\D\D\D	ABC
\W	One character that is not a word character as defined by your engine's \w	\W\W\W\W\W	*-+=)
\S	One character that is not a whitespace character as defined by your engine's \s	\S\S\S\S	Yoyo

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Quantifiers

Quantifier	Legend	Example	Sample Match
+	One or more	Version \w-\w+	Version A-b1_1
{3}	Exactly three times	\D{3}	ABC
{2,4}	Two to four times	\d{2,4}	156
{3,}	Three or more times	\w{3,}	regex_tutorial
*	Zero or more times	ABC*	AAACC
?	Once or none	plurals?	plural

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More Characters

Character	Legend	Example	Sample Match
.	Any character except line break	a.c	abc
.	Any character except line break	.*	whatever, man.
\.	A period (special character: needs to be escaped by a \)	a\.c	a.c
\	Escapes a special character	\.\*\+\? \$\^\/\\	.*+? $^/\
\	Escapes a special character	\[\{\}\]	[{()}]

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Logic

Logic	Legend	Example	Sample Match
\|	Alternation / OR operand	22\|33	33
( … )	Capturing group	A(nt\|pple)	Apple (captures "pple")
\1	Contents of Group 1	r(\w)g\1x	regex
\2	Contents of Group 2	(\d\d)\+(\d\d)=\2\+\1	12+65=65+12
(?: … )	Non-capturing group	A(?:nt\|pple)	Apple

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More White-Space

Character	Legend	Example	Sample Match
\t	Tab	T\t\w{2}	T ab
\r	Carriage return character	see below
\n	Line feed character	see below
\r\n	Line separator on Windows	AB\r\nCD	AB CD
\N	Perl, PCRE (C, PHP, R…): one character that is not a line break	\N+	ABC
\h	Perl, PCRE (C, PHP, R…), Java: one horizontal whitespace character: tab or Unicode space separator
\H	One character that is not a horizontal whitespace
\v	.NET, JavaScript, Python, Ruby: vertical tab
\v	Perl, PCRE (C, PHP, R…), Java: one vertical whitespace character: line feed, carriage return, vertical tab, form feed, paragraph or line separator
\V	Perl, PCRE (C, PHP, R…), Java: any character that is not a vertical whitespace
\R	Perl, PCRE (C, PHP, R…), Java: one line break (carriage return + line feed pair, and all the characters matched by \v)

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More Quantifiers

Quantifier	Legend	Example	Sample Match
+	The + (one or more) is "greedy"	\d+	12345
?	Makes quantifiers "lazy"	\d+?	1 in 12345
*	The * (zero or more) is "greedy"	A*	AAA
?	Makes quantifiers "lazy"	A*?	empty in AAA
{2,4}	Two to four times, "greedy"	\w{2,4}	abcd
?	Makes quantifiers "lazy"	\w{2,4}?	ab in abcd

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Character Classes

Character	Legend	Example	Sample Match
[ … ]	One of the characters in the brackets	[AEIOU]	One uppercase vowel
[ … ]	One of the characters in the brackets	T[ao]p	Tap or Top
-	Range indicator	[a-z]	One lowercase letter
[x-y]	One of the characters in the range from x to y	[A-Z]+	GREAT
[ … ]	One of the characters in the brackets	[AB1-5w-z]	One of either: A,B,1,2,3,4,5,w,x,y,z
[x-y]	One of the characters in the range from x to y	[ -~]+	Characters in the printable section of the ASCII table.
[^x]	One character that is not x	[^a-z]{3}	A1!
[^x-y]	One of the characters not in the range from x to y	[^ -~]+	Characters that are not in the printable section of the ASCII table.
[\d\D]	One character that is a digit or a non-digit	[\d\D]+	Any characters, inc- luding new lines, which the regular dot doesn't match
[\x41]	Matches the character at hexadecimal position 41 in the ASCII table, i.e. A	[\x41-\x45]{3}	ABE

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Anchors and Boundaries

Anchor	Legend	Example	Sample Match
^	Start of string or start of line depending on multiline mode. (But when [^inside brackets], it means "not")	^abc .*	abc (line start)
$	End of string or end of line depending on multiline mode. Many engine-dependent subtleties.	.*? the end$	this is the end
\A	Beginning of string (all major engines except JS)	\Aabc[\d\D]*	abc (string... ...start)
\z	Very end of the string Not available in Python and JS	the end\z	this is...\n...the end
\Z	End of string or (except Python) before final line break Not available in JS	the end\Z	this is...\n...the end\n
\G	Beginning of String or End of Previous Match .NET, Java, PCRE (C, PHP, R…), Perl, Ruby
\b	Word boundary Most engines: position where one side only is an ASCII letter, digit or underscore	Bob.*\bcat\b	Bob ate the cat
\b	Word boundary .NET, Java, Python 3, Ruby: position where one side only is a Unicode letter, digit or underscore	Bob.*\b\кошка\b	Bob ate the кошка
\B	Not a word boundary	c.\Bcat\B.	copycats

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POSIX Classes

Character	Legend	Example	Sample Match
[:alpha:]	PCRE (C, PHP, R…): ASCII letters A-Z and a-z	[8[:alpha:]]+	WellDone88
[:alpha:]	Ruby 2: Unicode letter or ideogram	[[:alpha:]\d]+	кошка99
[:alnum:]	PCRE (C, PHP, R…): ASCII digits and letters A-Z and a-z	[[:alnum:]]{10}	ABCDE12345
[:alnum:]	Ruby 2: Unicode digit, letter or ideogram	[[:alnum:]]{10}	кошка90210
[:punct:]	PCRE (C, PHP, R…): ASCII punctuation mark	[[:punct:]]+	?!.,:;
[:punct:]	Ruby: Unicode punctuation mark	[[:punct:]]+	‽,:〽⁆

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Inline Modifiers

None of these are supported in JavaScript. In Ruby, beware of (?s) and (?m).

Modifier	Legend	Example	Sample Match
(?i)	Case-insensitive mode (except JavaScript)	(?i)Monday	monDAY
(?s)	DOTALL mode (except JS and Ruby). The dot (.) matches new line characters (\r\n). Also known as "single-line mode" because the dot treats the entire input as a single line	(?s)From A.*to Z	From A to Z
(?m)	Multiline mode (except Ruby and JS) ^ and $ match at the beginning and end of every line	(?m)1\r\n^2$\r\n^3$	1 2 3
(?m)	In Ruby: the same as (?s) in other engines, i.e. DOTALL mode, i.e. dot matches line breaks	(?m)From A.*to Z	From A to Z
(?x)	Free-Spacing Mode mode (except JavaScript). Also known as comment mode or whitespace mode	(?x) # this is a # comment abc # write on multiple # lines [ ]d # spaces must be # in brackets	abc d
(?n)	.NET, PCRE 10.30+: named capture only	Turns all (parentheses) into non-capture groups. To capture, use named groups.
(?d)	Java: Unix linebreaks only	The dot and the ^ and $ anchors are only affected by \n
(?^)	PCRE 10.32+: unset modifiers	Unsets ismnx modifiers

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Lookarounds

Lookaround	Legend	Example	Sample Match
(?=…)	Positive lookahead	(?=\d{10})\d{5}	01234 in 0123456789
(?<=…)	Positive lookbehind	(?<=\d)cat	cat in 1cat
(?!…)	Negative lookahead	(?!theatre)the\w+	theme
(?<!…)	Negative lookbehind	\w{3}(?<!mon)ster	Munster

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Character Class Operations

Class Operation	Legend	Example	Sample Match
[…-[…]]	.NET: character class subtraction. One character that is in those on the left, but not in the subtracted class.	[a-z-[aeiou]]	Any lowercase consonant
[…-[…]]	.NET: character class subtraction.	[\p{IsArabic}-[\D]]	An Arabic character that is not a non-digit, i.e., an Arabic digit
[…&&[…]]	Java, Ruby 2+: character class intersection. One character that is both in those on the left and in the && class.	[\S&&[\D]]	An non-whitespace character that is a non-digit.
[…&&[…]]	Java, Ruby 2+: character class intersection.	[\S&&[\D]&&[^a-zA-Z]]	An non-whitespace character that a non-digit and not a letter.
[…&&[^…]]	Java, Ruby 2+: character class subtraction is obtained by intersecting a class with a negated class	[a-z&&[^aeiou]]	An English lowercase letter that is not a vowel.
[…&&[^…]]	Java, Ruby 2+: character class subtraction	[\p{InArabic}&&[^\p{L}\p{N}]]	An Arabic character that is not a letter or a number

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Other Syntax

Syntax	Legend	Example	Sample Match
\K	Keep Out Perl, PCRE (C, PHP, R…), Python's alternate regex engine, Ruby 2+: drop everything that was matched so far from the overall match to be returned	prefix\K\d+	12
\Q…\E	Perl, PCRE (C, PHP, R…), Java: treat anything between the delimiters as a literal string. Useful to escape metacharacters.	\Q(C++ ?)\E	(C++ ?)

Don't Miss The Regex Style Guide

and The Best Regex Trick Ever!!!

The 1001 ways to use Regex

Ask Rex

Leave a Comment

1-5 of 5 Threads

Ilya – Russia

August 27, 2017 - 20:19

Subject: a correction to the article

Hello, Rex, and thank you very much for the site. It should probably be noted in the article that in pcre2test the modifier "C" is changed to "auto_callout", so if one downloads the latest compiled version (it's 10.22 at the moment) of pcretest linked from the page and tries the example pattern (~\btoto(\w+)\b~C) you gave, pcre2test throws the "** Unrecognized modifier 'C' in 'C'" error. It took me a while to figure out what the problem is :)

Please don't publish this message, just correct the article if you think you should. Ilya.

NewWorld – Germany

March 11, 2014 - 03:07

Subject: Many thanks

I was having problems with Cygwin's grep and multi-line patterns, so thanks for the recommendation to use pcregrep instead. I love your site; everything is explained clearly. I finally learnt how to use lookaheads and behinds thanks to your clear instructions. Really great site. Thanks again.

Glen

February 13, 2014 - 05:55

Subject: problem with pcregrep for Windows

I tried the latest version on your site, saying:

pcregrep the pcregrep.txt

It prints every line of the input. If I use an invalid pattern like "zzz", it prints nothing.

Reply to Glen

Rex

February 13, 2014 - 09:39

Subject:

Hi Glen,

That sounds like expected behavior... if each line of the input contains "the". Is that not the case? Remember that a "line" can take several screen lines up to the next carriage return.
I tested what you said, and if I remove "the" from one of the lines of input, that line does not show in the output (as expected).
If you want to see more sober output, you can try something like

pcregrep -no the test.txt

For how this works, please see the examples on the page, as well as the documentation inside the zip file.

Warm regards,

Andy

Cesar Romani

December 21, 2013 - 17:50

Subject: pcregrep doesn't work

I'm using pcregrep on Windows 7. I have a folder with text files in utf-8 encoding, which contain the word "español. " If I open cmd on that folder and do:
pcregrep -u -I español *.txt

I don't get anything. Many thanks in advance,

—
Cesar

Reply to Cesar Romani

Andy

December 21, 2013 - 20:28

Subject: RE: pcregrep doesn't work

Hi Cesar, pcregrep works. Your PCRE syntax is not correct. No time to help you, please download the regexbuddy demo from the right column of my website to troubleshoot your PCRE syntax. Cordially, Rex

Gary

December 11, 2013 - 16:13

Subject: using --color with cmd.exe

There are a few ways to use the —color flag in cmd.exe. I used to use rlwrap.exe from cygwin but it had a few cygwin dependencies and was a bit heavy for just wrapping grep. If you wanted to wrap a full readline in cmd.exe it works great though. Now I use ansicon and it's very simple and much faster than rlwrap was. You can get the source from github under adoxa/ansicon and compile or they have a prebuilt one you can download. It's builds a single exe and 2 dll's (x86 & x64). I just run it like "ansicon.exe grep —color toto *" which just uses it for that one command. You can also run ansicon.exe by itself to enable for the current cmd.exe or you can install to autorun so it runs on every new cmd.exe. You can also use color prompts or other tools with ansi color output. I enjoyed your article and the info on pcretest, which was exactly what I was looking for.

Reply to Gary

Rex

December 22, 2013 - 18:52

Subject: RE: using --color with cmd.exe

Hi Gary, Thanks for the great tip! Wishing you a fun weekend, Rex