Snippets/Regular Expressions Cheat Sheet.md

Regular Expressions Cheat Sheet

A regular expression specifies a set of strings that matches it. This cheat sheet is based off Python 3's Regular Expressions (http://docs.python.org/3/library/re.html) but is designed for searches within Sublime Text.

https://gist.github.com/IsaacCisneros/d7f3cf4bf6c0573d0570

https://ahkde.github.io/docs/v1/misc/RegEx-QuickRef.htm

https://serverdiscounter.com/blog/2026-01-26-regex-grundlagen

Special Characters

\	Escapet Sonderzeichen oder kennzeichnet eine spezielle Sequenz
.	Entspricht einem beliebigen einzelnen Zeichen mit Ausnahme eines Zeilenumbruchs
^	Matches the start of the string.
$	Matches the end of the string​
*	Greedily matches 0 or more repetitions of the preceding RE.
*?	Matches 0 or more repetitions of the preceding RE.
+	Greedily matches 1 or more repetitions of the preceding RE.
+?	Matches 1 or more repetitions of the preceding RE.
?	Greedily matches 0 or 1 repetitions of the preceding RE.
??	Matches 0 or 1 repetitions of the preceding RE.
A|B	Matches A, if A is unmatched then matches B, where A and B are arbitrary REs.
{m}	Matches exactly m many repetitions of the previous RE.
{m,n}	Greedily matches from m many to n many repetitions of the previous RE.
{m,n}?	Matches m many to n many repetitions of the previous RE.

​

[...] Indicates a set of characters to match. [amk] Matches 'a', 'm', or 'k'. [a-z] Matches 'a' through 'z'. [a-f0-7] Matches 'a' through 'f' or '0' through '7'. [a-z] Matches 'a', '-', or 'z'. [a-] Matches 'a' or '-'. [-a] Matches 'a' or '-'. [(+)] Matches '(', '+', '', or ')'. [] matches special characters literally. [\w] Matches the character class for '\w'. See character classes. [^5] Matches anything other than '5'. '^' forms the complementary set only as the first character in a set. ] Matches ']', '(', and ')'. ']' is taken literally only as the first character in a set. [()]] Matches ']', '(', and ')'.

(...) Matches the RE inside the parenthesis and assigns a new group. (?P...) The RE matched is accessible by the group indicated by name.

(?...) Extension notation which changes a RE's behavior. These do not assign a new group. (?aiLmsux) Sets the corresponding flag to each letter. Does not work within Sublime Text. (?:...) A non-capturing version of parenthesis. The matched substring cannot be retrieved later. (?P=name) Matches the substring matched by the group named name. (?#...) A comment, the contents are ignored. (?=...) Lookahead assertion, the preceding RE only matches if this matches. (?!...) Negative lookahead assestion, the preceding RE only matches if this doesn't match. (?<=...) Positive lookbehind assertion, the following RE will only match if preceeded with this fixed length RE. (?<!...) Negative lookbehind assertion, the following RE will only match if not preceeded with this fixed length RE. (?(id)true|false) If group id exists then uses the true RE, else use the false RE.

Character classes \1 Matches the contents of the group labelled by the same number. Acceptable numbers are 1-99. \A Matches at the start of the current string. \b Matches the empty string at the beginning or end of a word. \b matches the boundary between \w and \W. \B Matches the empty string not at the beginning or end of a word. \d Matches any Unicode decimal digit, including 0-9. \D Matches any Unicode non-decimal digit. \s Matches any Unicode whitespace character, including ' ', \t, \n, \r, \f and \v. \S Matches any Unicode non-whitespace character. \w Matches any Unicode word character, including a-z, A-Z, and 0-9. \W Matches any Unicode non-word character. \Z Matches at the end of the string.

\a Matches the ASCII Bell (). \f Matches the ASCII Formfeed (). \n Matches the ASCII Linefeed. \r Matches the ASCII Carriage Return ( ). \t Matches the ASCII Horizontal Tab. \v Matches the ASCII Vertical Tab ().

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Regular Expression Cheat Sheet with Examples

Regular Expressions (regex) are patterns used to match strings in text. Below is a cheat sheet with common regex patterns and examples.

1. Anchors

Pattern	Description	Example	Matches
^	Start of the string	^Hello	Hello world!
$	End of the string	world$	Hello world!

---

2. Quantifiers

Pattern	Description	Example	Matches
*	0 or more	a*	aaa, b
+	1 or more	a+	aaa, but not b
?	0 or 1	colou?r	color, colour
{n}	Exactly n occurrences	a{3}	aaa, but not aa
{n,}	At least n occurrences	a{2,}	aa, aaa
{n,m}	Between n and m occurrences	a{2,3}	aa, aaa, but not a

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3. Character Classes

Pattern	Description	Example	Matches
.	Any character except newline	a.b	acb, a9b
\d	Any digit (0-9)	\d+	123, 9
\D	Any non-digit	\D+	abc, @#
\w	Any word character (alphanumeric or _)	\w+	hello_123
\W	Any non-word character	\W+	@!, #
\s	Any whitespace	\s+	, \t, \n
\S	Any non-whitespace	\S+	abc, 123

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4. Logical OR and Grouping

Pattern	Description	Example	Matches
`a	b`	Match either a or b	`cat
`(ab	cd)`	Grouping	`(ab

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5. Escape Characters

Pattern	Description	Example	Matches
\.	Literal dot	a\.b	a.b
\[	Literal [	\[abc\]	[abc]

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6. Ranges

Pattern	Description	Example	Matches
[a-z]	Lowercase letters	[a-z]+	abc, xyz
[A-Z]	Uppercase letters	[A-Z]+	ABC, XYZ
[0-9]	Digits	[0-9]+	123, 456
[a-zA-Z0-9_]	Alphanumeric and underscore	\w+	hello123_

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7. Special Sequences

Pattern	Description	Example	Matches
(?=...)	Positive lookahead	foo(?=bar)	foo in foobar
(?!...)	Negative lookahead	foo(?!bar)	foo in foobaz
(?<=...)	Positive lookbehind	(?<=foo)bar	bar in foobar
(?<!...)	Negative lookbehind	(?<!foo)bar	bar in bazbar

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8. Common Patterns

Use Case	Regex	Example
Match email	[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}	user@example.com
Match URL	https?://[^\s]+	https://example.com
Match phone number	\d{3}-\d{3}-\d{4}	123-456-7890
Match date (YYYY-MM-DD)	\d{4}-\d{2}-\d{2}	2024-12-13

---

9. Flags

Flag	Description	Example
i	Case-insensitive	/hello/i matches Hello
g	Global match	/hello/g matches all hello
m	Multiline	/^hello/m matches per line

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10. Examples in Code

Python Example:

import re
# Match an email
pattern = r"[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}"
email = "contact@example.com"
print(re.match(pattern, email))  # Output: <re.Match object>

JavaScript Example:

// Match a URL
let pattern = /https?:\/\/[^\s]+/g;
let text = "Visit https://example.com for more info.";
console.log(text.match(pattern)); // Output: [ 'https://example.com' ]

regular-expressions-v2.pdf

regular-expressions-cheat-sheet-v1.pdf

regex-cheatsheet.pdf