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Regular Expressions Cheat Sheet by

A quick reference guide for regular expressions (regex), including symbols, ranges, grouping, assertions and some sample patterns to get you started.
               

Anchors

^
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

Character Classes

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

POSIX

[:upper:]
Upper case letters
[:lower:]
Lower case 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

Assertions

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

Quanti­fiers

*
0 or more
{3}
Exactly 3
+
1 or more
{3,}
3 or more
?
0 or 1
{3,5}
3, 4 or 5
Add a ? to a quantifier to make it ungreedy.

Escape Sequences

\
Escape following character
\Q
Begin literal sequence
\E
End literal sequence
"­Esc­api­ng" is a way of treating characters which have a special meaning in regular expres­sions literally, rather than as special charac­ters.

Common Metach­ara­cters

^
[
.
$
{
*
(
\
+
)
|
?
<
>
The escape character is usually \

Special Characters

\n
New line
\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 new line (\n)
(a|b)
a or b
(...)
Group
(?:...)
Passive (non-c­apt­uring) group
[abc]
Range (a or b or c)
[^abc]
Not (a or b or c)
[a-q]
Lower case letter from a to q
[A-Q]
Upper case letter from A to Q
[0-7]
Digit from 0 to 7
\x
Group/­sub­pattern number "­x"
Ranges are inclusive.

Pattern Modifiers

g
Global match
i *
Case-i­nse­nsitive
m *
Multiple lines
s *
Treat string as single line
x *
Allow comments and whitespace in pattern
e *
Evaluate replac­ement
U *
Ungreedy pattern
* PCRE modifier

String Replac­ement

$n
nth non-pa­ssive group
$2
"­xyz­" in /^(abc­(xy­z))$/
$1
"­xyz­" in /^(?:a­bc)­(xyz)$/
$`
Before matched string
$'
After matched string
$+
Last matched string
$&
Entire matched string
Some regex implem­ent­ations use \ instead of $.
 

Comments

Your regex cheatsheet says ^ is "Start of string" and $ is "End of string"

DaveChild DaveChild, 10:02 28 Nov 11

Hi Doug. I've clarified that section. Thanks for the heads up :)

, 10:02 28 Nov 11

It looks unchanged to me. ^ still says it's "start of string" and $ still says "end of string". They should be reversed, right?

, 10:02 28 Nov 11

Actually, I'm sorry, you're right! I was pretty confused there, sorry if I've confused anyone else.

DaveChild DaveChild, 10:02 28 Nov 11

No worries Keith - easy mistake to make!

Can you tag this as 'regex'? Searching for regex on cheatography yields two other results, but not this one.

Would you add \Q... \E to the cheatsheet?

It would be nice to see the list of white space characters

Great resource! Thanks for putting this together and sharing.

What language/flavor is this? Or I should also ask, if non is specified, what tends to be the default? I'm specifically looking for php or javascript, and I know they're all mostly the same, but not 100%.

Thanks!

David, Regex is programming language neutral, as in, it doesn't matter if you are programming regex expressions in javascript, c#, c++, PHP, or even command line *nix, makes no difference. Only thing you have to watch out for is some programming languages may require different various regex characters to be escaped differently (so the programming language doesn't try to interpret it). Usually a backslash. For instance \\ means ONE backslash in many languages.

BillSmith BillSmith, 20:27 30 Jan 18

Chris, I am a bit confused.

At the following URL (https://www.regular-expressions.info/cookbook.html), I just read this:

"The book covers the regular expression flavors .NET, Java, JavaScript, XRegExp, Perl, PCRE, Python, and Ruby, and the programming languages C#, Java, JavaScript, Perl, PHP, Python, Ruby, and VB.NET. After a quick introduction, the book starts with a detailed regular expressions tutorial which equally covers all 8 regex flavors."

I am having trouble squaring the quoted statement with what you wrote above.

Thanks.

Very handy, thank you!

Don't forget Perl ;-)

Great and useful stuff!

Hi, I'm trying to learn REGEX, and I need to find this: "Page 1 Of 60", ..... "Page 50 of 60", But I can't find it using reg. expressions! :(. How would you do that? Thank you!

Is there a cheat sheet to the cheat sheet? Is this in plain english anywhere?..."negative lookahead"..huh?

@david, this cheat sheet is pretty neutral. The most common flavor is Perl Compatible Regular Expressions (PCRE). Javascript's engine is close to that and PHP also has Perl Compatible functions for Regex; they use the PREG prefix. Most everything on this sheet should be supported by PHP's engine (I think POSIX character classes are not). Javascript's engine isn't as featureful. Some advanced features aren't supported, but all the basics are there. If you need a multiline match and you can't use the flag, you can use an inverted class range such as [\s\S] in place of the . (dot) to match anything including newlines.

@Chilean+kris w, You need to find a resource for learning Regular Expressions. This cheat sheet is for reference, not learning. Check out http://www.regular-expressions.info/

I was confused by the first comment (which was wrong, but you compounded the error with an acknowlegement). ^ is the start of string or line. Period.

Also, your cheat sheet is better organized than the more comprehensive http://www.regular-expressions.info/
since its more succinct. The latter has a 1-page summary but its too verbose.

Nice sheet.

Is there a reason why the ']' character is not listed under metacharacters? Doesn't that character require to be escaped if searched for?

Hey Dave. Thanks for the cheat sheet. You may want to change "Not a or b or c" when you describe the [^abc} negated character class, because in English, the negation is ambiguous. It could mean "neither a nor be nor c." Or the "a" could be the only negated disjunct. You could mean (~a v (b v c)).

Could be added to the list.

Case Conversion
\l Make next character lowercase
\u Make next character uppercase
\L Make entire string (up to \E) lowercase
\U Make entire string (up to \E) uppercase
\u\L Capitalize first char, lowercase rest (sentence)

I have a database using regex. I am trying to use ^file to get all files with name file_,file ,file_name_date. but it is not working any help

Is \x supported anywhere? I can't find examples of it in use searching the web. It also does not work in a script on my Macintosh, OSX 10.7.5 using the OS's perl installation.

I'm trying to come up with a regex string to filter results to a directory that includes a-zA-Z but that also includes an underscore ('_'). Do you know of a way to do this?

Is \x supported anywhere? I can't seem to find where it is supported. E.g., perl on MacOS 10.7.5. Searching for on-line examples or help also fails, in that no one knows about it.

Is \x (Regular Expressions Character Classes) supported anywhere? Is this a new class that has just been added, because I am unable to use it in working with IPV6 addresses. Searching for a string containing something like 2001::1a79 with a RegEx 2001::\x{1,4} will fail, but if I use 2001::[a-fA-F0-9]{1,4} will work.

\x is a term in "Regular Expressions Character Classes" for an hexadecimal digit. How does this compare to the \xhh "Special Characters"? Is it supported today?

It would be great to increase in some ways the --> : <---- in the
"(?:...) Passive (non-c­apt­uring) group" description. Just after the "?", it is praticaly not visible. Thanks!

This is a great cheat-sheet. Two minor niggles:
* Would be great to hint on the characters hidden in the character classes (\s = [ \t\n\r\f], \d = [0-9], \w = [a-zA-Z_0-9])
* I think possibly there's a mistake in the section "Special Characters" - \xxx is probably not the octal character xxx. See "Character Classes": it should be \Oxxx (and by the way: why are \O and \x duplicated in "Special Characters" and "Character Classes"...)
And I support Edir's request for a section "Case Conversion".
But again: great sheet, thanks!

Thank you for the Regex cheat sheet :-)

Thank you. It would have been better if you would have included test, match, etc.

Does these support ereg too?

what is mean by (.*?) please let me know as soon as possible ??

There are so many dialects of regex. The most important fact should be right up top, which dialects do you cover?

Can you please fix the pdf so it is able to download? Right now my browser (Google Chrome) only show a raw pdf instead of downloading it. Thank you very much :)

I agree with Roedy Green. I came here looking for specific a version of regex. This is still so helpful.

Ted, when the PDF displays in Chrome, right-click in the page and select Save As.

Hi ,
Can u help me to find regular expression --

SELECT distinct col_1 FROM tablename
WHERE (SUBSTR(col_1,-1,1)) = '5'

need resuslt as abc-cxy-5

not as abc-cxy-65
not as abc-cxy-555
not as abc-cxy-05545

Hello Jaya,
MySQL supports regular expressions:
select distinct col_1
from tablename
where col_1
REGEXP '[a-z]{3}-[a-z]{3}-5'

Great Cheatsheet. Maybe you could add the toggles like (?i...), (?-i...), (?i: ...), (?-i: ...) and their cousins with "m" and "x".

THanks for the great work

Thank you for this !!

Nice cheat sheet, great job !

Hi Team,

How to write a regular expression for this kind of below line present in document .

Ref: 000/SP/00-000

I need to set Target data formats and Keywords for this field.

Thanks in advance.

I have been searching for programs that others might be using to roll dice in Pachisi on the internet. I know nothing about programming and don't know how to word the question. Are there cheat sheets out there for something like this?

If you like this you may want to check out my tutorial on how to use regular expressions in Ruby :) http://www.blackbytes.info/2015/06/mastering-ruby-regex/

Thanks for the great job!

Thanks for the nice and comprehensive resource.

Hi I am a techno retard I gather Regex is coding flavour. However I have no idea what you write is there sny resources.

Sorry for stupidity.

Philbo.

Great list! I'm new to Teradata Regular Expressions and couldn't find them anywhere.

Very helpful. Thanks.

I am finding it difficult to write a regex for the date input..it looks like this...[31-Mar-2015:06:22:48 -600]. I am trying with [0-9a-zA-Z) but giving me null values. Please help.

I need to split a group of elment baased on "," delimiter this is the example
input :"(10,{10,9,8,7,6,5,4,3,2,1}),(8,{8,7,6,5,4,3,2,1}),(8,{8,7,6,5,4,3,2,1})
output: (10,{10,9,8,7,6,5,4,3,2,1})
(8,{8,7,6,5,4,3,2,1})
(8,{8,7,6,5,4,3,2,1}) regex: [()], which is not getting me in the way i want.

Do you have any issue with us distributing the PDF regex cheat sheet as is with no changes to others. Before I put it on our internal collaboration tool I need to make sure there are no issues from you in doing so. I will not be modifying the PDF or removing your details from the sheet, it will be just as it is but shareable from within our company's portal.

DaveChild DaveChild, 15:31 5 Mar 16

It's released (as all cheat sheets here are) under a CC license, so you can redistribute it according to the terms here:

http://creativecommons.org/licenses/by-nc-sa/2.0/uk/

So, go for it :)

Shrirang: What're you trying to do with the date? Just capture it?

I don't know how detailed you want to be, but this'll capture everything in what you posted. For experienced people it's probably really inelegant, but it's functional, anyway:

(\[)(\d{2})(\-)([A-Z]+)(\-)(\d{4})(\:\d{2}\:\d{2}\:\d{2})(\s+)(\-\d+)(\])

Pradeep: I was able to accomplish what you're looking for with the following text (I'm using Notepad++):

Search: (\))(,)
Replace: \1\r\n\2

Hi Dave - could you an entry for free whitespace regexes using the ?x syntax?

Hello Guys,

I am trying to create a code to prevent white spaces before or after a string.

[ name ]
[ name]
[name ]

Ideally I want this to be strictly

[Name]

How can i achieve that?

Hi Folks! I use regexp syntax to schedule TV recordings via TVHeadend which is case-insensitive by default.
Here's an extreme example which highlights the problem.

Simply using 'big brother' produces many different program name matches like:
Big Brother
Big Brother's Bit On The Side
Big Brother: Annihilation
Big Brother: Eviction Massacre
New: Big Brother
New: Big Brother's Bit On The Side
New: Big Brother: Live...

I'd like to tell it to ignore the Bit On The Side programs but match the rest. I've researched till I'm blue in the face with no luck.

My tiny brain tells me that in regular English it would read like this:
match 'big brother' but not if contains 'bit on the side'
but I'm lost when it comes to translating this to regexp syntax.
I honestly don't know if it accepts Lookahead or Lookbehind which I see is mentioned a lot, sorry.

Any geniuses out there got any ideas? Much appreciated.

Cảm ơn | Thanks!

better clarify which syntax flavor this cheatsheet is about, is it BRE? ERE or PCRE?

Can you talk about flag in Regex, sir?
Specially, it is flag Y. And it will be great if there is examples.
Anyway, thank you so much.

Greetings, and thanks for providing this.

Where can I find a comprehensive, accessible textual reference on this topic that includes numerous examples? Instead of pursuing blind trial and error, I would like to understand thoroughly what I am doing, and why.

Thanks.

Thanks for this valuable document

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