Regular Expressions Cheat Sheet

Edit me

Wildcards

Pattern	Meaning
.	Any character
\w	Word character: letters, numbers, and _
\W	Non-word character
\s	White space: space, tab, or end of line (EOL)
\S	Non-white space character
\d	Digit character, but not the . in 2.4
\D	Non-digit character
\t	Tab character
\n	Newline character, though some tools use \r
\\	\ is the escape character, so \\ matches \, \^ matches ^, and so on

Repetitions

Pattern	Meaning
*	Match 0 or more times
+	Match 1 or more times
?	Non-greedy: get the shortest match
{n}	Match exactly n times
{n,}	Match at least n times
{n,m}	Match at least n, but not more than m times

Character Classes

Pattern	Meaning
[AEIOU]	Match 1 vowel character
[A-Z]	Match 1 capital letter
[A-Za-z0-9_]	Same as \w
^[A-Za-z]	Match 1 letter at the beginning of a string or line
[^A-Za-z]	Match any character that is not a letter, including EOL. Note the very different meaning here. Inside [], ^ means NOT.

Boundary Qualifiers

Pattern	Meaning
^	Match at the start of a string or line
$	Match at the end of a string or line
^ABC$	Exact match to ABC - Both starts and ends in ABC

Capturing And Replacing

Pattern	Meaning
()	Capture the search results between parentheses and save for later use. If there are multiple or nested groups, numbering follows the order of (.
$1, $2	Variables containing captured text, numbered by the order of (. These can be used in replacements. Some editors, such as BBEdit, use \1, \2, and so on.

Some Examples

Sample text: This is 1.0 (one) line to play with

Pattern	Matches	Notes
\w*	This
\d+	1
[0-9\.]+	1.0
((\w*)\s(\w*))	$1 = “This is”, $2 = “This”, $3 = “is”
\w*$	with
is\s{2}	is is	from “This is”
\(.+\)	(one)	Note the escaping of the parentheses
\w+?	T	Note the non-greediness of ?
\w*?	Blank match	Why?