Regular Expressions Cheatsheet

Get new articles automatically


^ Start of string
\A Start of string
$ End of string
\Z End of string
\b Word boundary
\B Not word boundary
\< Start of word
\> End of word
\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
?= Lookahead assertion
?! Negative lookahead
?<= Lookbehind assertion
?!= or also ? Negative lookbehind
?> Once-only Subexpression
?() Condition [If Then]
?()| Condition [If Then Else]
?# Comment
* 0 or more occurences
+ 1 or more occurences
? 0 or 1 occurences
{5} Exactly 5 occurences (or any other number instead of 5)
{5,} 5 or more occurences
{5,8} 5, 6, 7 or 8 occurences
x? Ungreedy version of “x”, where x is a quantifier (see before)
/ Escape one character
Note that all of these characters need to be escaped (see escape character above)
^ $ ( ) < >
[ { \ | . *
+ ?
g Global match
i Make case-insensitive
m Match multiple lines
s Treat a string as a single line
x Allow the occurence of whitespace and comments in the string
e Evaluate the replacement
U Use an Ungreedy pattern
\n Newline
\r Carriage return
\t Tab
\v Vertical tab
\f Form feed
\xxx Octal character xxx
\xhh Hex character hh
. Matches all characters except newline
(x|y) Matches x or y
(...) A group, matches the group exactly (xyz) matches 'xyz'
(?:...) Lazy group, matches every occurence of group, not only the first and the last (as greedy does)
[xyz] Range, matches x, y or z
[^xyz] Negative range, matches NOT x, y or z
[a-z] Matches any letter between a and z
[A-Z] Matches any upper case letter between a and z
[0-9] Matches any number between 0 and 9 (digit)
\x Matches the “x”-th occurence of the pattern
$x Replaces “x”-th non-passive group that matches
$2 Replaces “def” in /^(abc(def))$/
$1 Replaces “def” in /^(?:abc(def))$/
$` Replaces before the matched string
$’ Replaces after the matched string
$+ Replaces the last matched string
$& Replaces the entire matched string


Related posts:

  1. PHP Lesson 2: Data types Today’s PHP lesson is about data types....
  2. HTML Cheatsheet Try this page for a list of...
  3. Recognizing the iPhone for webpages As said in my 2009 predictions, the...

Get new articles automatically

There are no comments yet. Be the first and leave a response!

Leave a Reply


Wanting to leave an <em>phasis on your comment?

CommentLuv Enabled
Trackback URL http://www.icantinternet.org/2008/03/regular-expressions-cheatsheet/trackback/

Bad Behavior has blocked 836 access attempts in the last 7 days.