Regex Cheat Sheet

A comprehensive reference guide for Regular Expressions (regex) with patterns, examples, and detailed explanations. Perfect for developers, data analysts, and anyone working with text processing.

39 patterns found

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`literal text`

Basic

Match exact characters

Pattern:

text

Examples:

hello Matches the exact string 'hello'

123 Matches the exact number '123'

Hello World Matches 'Hello World' exactly (case sensitive)

Notes:

Most characters match themselves literally

`. (dot)`

Basic

Match any single character except newline

Pattern:

.

Examples:

h.llo Matches 'hello', 'hallo', 'h3llo', etc.

a.b Matches 'axb', 'a b', 'a5b', etc.

.... Matches any 4 characters

Notes:

Use \. to match a literal dot

`\`

Basic

Escape special characters

Pattern:

\character

Examples:

\. Matches a literal dot

\$ Matches a literal dollar sign

\\ Matches a literal backslash

\( Matches a literal opening parenthesis

Notes:

Backslash removes special meaning from metacharacters

`[abc]`

Character Classes

Match any one character from the set

Pattern:

[characters]

Examples:

[abc] Matches 'a', 'b', or 'c'

[0-9] Matches any digit from 0 to 9

[a-zA-Z] Matches any letter (upper or lowercase)

[aeiou] Matches any vowel

Notes:

Square brackets define a character class

`[^abc]`

Character Classes

Match any character NOT in the set

Pattern:

[^characters]

Examples:

[^abc] Matches any character except 'a', 'b', or 'c'

[^0-9] Matches any non-digit character

[^aeiou] Matches any consonant

[^\s] Matches any non-whitespace character

Notes:

Caret ^ at the beginning negates the character class

`\d`

Character Classes

Match any digit (0-9)

Pattern:

\d

Examples:

\d Matches '0', '1', '2', ..., '9'

\d\d Matches any two-digit number

\d+ Matches one or more digits

Notes:

Equivalent to [0-9]

`\D`

Character Classes

Match any non-digit character

Pattern:

\D

Examples:

\D Matches 'a', 'B', '!', ' ', etc.

\D+ Matches one or more non-digit characters

\d\D Matches a digit followed by a non-digit

Notes:

Equivalent to [^0-9]

`\w`

Character Classes

Match any word character (letters, digits, underscore)

Pattern:

\w

Examples:

\w Matches 'a', 'Z', '5', '_'

\w+ Matches one or more word characters

\w{3} Matches exactly 3 word characters

Notes:

Equivalent to [a-zA-Z0-9_]

`\W`

Character Classes

Match any non-word character

Pattern:

\W

Examples:

\W Matches '!', '@', ' ', '-', etc.

\w+\W Matches word characters followed by non-word character

\W+ Matches one or more non-word characters

Notes:

Equivalent to [^a-zA-Z0-9_]

`\s`

Character Classes

Match any whitespace character

Pattern:

\s

Examples:

\s Matches space, tab, newline, etc.

\s+ Matches one or more whitespace characters

\w+\s+\w+ Matches two words separated by whitespace

Notes:

Includes space, tab, newline, carriage return, form feed

`\S`

Character Classes

Match any non-whitespace character

Pattern:

\S

Examples:

\S Matches any visible character

\S+ Matches one or more non-whitespace characters

\S\s\S Matches non-space, space, non-space

Notes:

Any character except whitespace

`+`

Quantifiers

Match one or more of the preceding character

Pattern:

pattern+

Examples:

a+ Matches 'a', 'aa', 'aaa', etc.

\d+ Matches one or more digits

[a-z]+ Matches one or more lowercase letters

Notes:

Greedy quantifier - matches as many as possible

`*`

Quantifiers

Match zero or more of the preceding character

Pattern:

pattern*

Examples:

a* Matches '', 'a', 'aa', 'aaa', etc.

\d* Matches zero or more digits

.* Matches any characters (including empty string)

Notes:

Greedy quantifier - matches as many as possible

`?`

Quantifiers

Match zero or one of the preceding character

Pattern:

pattern?

Examples:

colou?r Matches 'color' or 'colour'

\d? Matches zero or one digit

https? Matches 'http' or 'https'

Notes:

Makes the preceding character optional

`{n}`

Quantifiers

Match exactly n occurrences

Pattern:

pattern{n}

Examples:

\d{3} Matches exactly 3 digits

a{5} Matches exactly 5 'a' characters

[0-9]{4} Matches exactly 4 digits (like a year)

Notes:

Exact repetition count

`{n,m}`

Quantifiers

Match between n and m occurrences

Pattern:

pattern{n,m}

Examples:

\d{2,4} Matches 2, 3, or 4 digits

a{1,3} Matches 'a', 'aa', or 'aaa'

[a-z]{3,6} Matches 3 to 6 lowercase letters

Notes:

Range of repetitions

`{n,}`

Quantifiers

Match n or more occurrences

Pattern:

pattern{n,}

Examples:

\d{3,} Matches 3 or more digits

a{2,} Matches 'aa', 'aaa', 'aaaa', etc.

\w{5,} Matches 5 or more word characters

Notes:

Minimum repetition count

`^`

Anchors

Match start of string/line

Pattern:

^pattern

Examples:

^Hello Matches 'Hello' only at the beginning

^\d+ Matches digits at the start of line

^[A-Z] Matches uppercase letter at beginning

Notes:

Anchors the match to the beginning of the string or line

`$`

Anchors

Match end of string/line

Pattern:

pattern$

Examples:

end$ Matches 'end' only at the end

\d+$ Matches digits at the end of line

\.$ Matches a period at the end

Notes:

Anchors the match to the end of the string or line

`\b`

Anchors

Match word boundary

Pattern:

\bpattern\b

Examples:

\bcat\b Matches 'cat' as a whole word, not 'category'

\btest Matches 'test' at the beginning of a word

ing\b Matches 'ing' at the end of a word

Notes:

Boundary between word (\w) and non-word (\W) characters

`\B`

Anchors

Match non-word boundary

Pattern:

\Bpattern\B

Examples:

\Bcat\B Matches 'cat' within a word, like in 'category'

\Btest Matches 'test' NOT at word boundary

ing\B Matches 'ing' NOT at word end

Notes:

NOT at word boundary - within a word

`(pattern)`

Groups

Create capturing group

Pattern:

(pattern)

Examples:

(abc)+ Matches 'abc', 'abcabc', 'abcabcabc', etc.

(\d{2})-(\d{2})-(\d{4}) Captures date parts: MM-DD-YYYY

(Mr|Mrs|Ms)\.\s+(\w+) Captures title and name

Notes:

Groups patterns and captures matched text for later use

`(?:pattern)`

Groups

Create non-capturing group

Pattern:

(?:pattern)

Examples:

(?:abc)+ Groups 'abc' but doesn't capture

(?:http|https):// Matches protocol without capturing

(?:Mr|Mrs|Ms)\.\s+(\w+) Groups title but only captures name

Notes:

Groups patterns but doesn't create a capture group

`|`

Groups

Match one pattern OR another

Pattern:

pattern1|pattern2

Examples:

cat|dog Matches either 'cat' or 'dog'

jpeg|jpg|png Matches any of these image extensions

(Mr|Mrs|Ms) Matches any of these titles

Notes:

Logical OR operator - matches either side

`(?=pattern)`

Lookaround

Positive lookahead - match if followed by pattern

Pattern:

pattern(?=lookahead)

Examples:

\w+(?=@) Matches username before @ in email

\d+(?=px) Matches numbers followed by 'px'

hello(?=\s+world) Matches 'hello' only if followed by ' world'

Notes:

Assertion - doesn't consume characters, just checks what follows

`(?!pattern)`

Lookaround

Negative lookahead - match if NOT followed by pattern

Pattern:

pattern(?!lookahead)

Examples:

\w+(?!@) Matches words NOT followed by @

\d+(?!px) Matches numbers NOT followed by 'px'

hello(?!\s+world) Matches 'hello' NOT followed by ' world'

Notes:

Assertion - matches only if NOT followed by the pattern

`(?<=pattern)`

Lookaround

Positive lookbehind - match if preceded by pattern

Pattern:

(?<=lookbehind)pattern

Examples:

(?<=@)\w+ Matches domain after @ in email

(?<=\$)\d+ Matches numbers preceded by $

(?<=hello\s)\w+ Matches word after 'hello '

Notes:

Assertion - checks what comes before the match

`(?<!pattern)`

Lookaround

Negative lookbehind - match if NOT preceded by pattern

Pattern:

(?<!lookbehind)pattern

Examples:

(?<!@)\w+ Matches words NOT preceded by @

(?<!\$)\d+ Matches numbers NOT preceded by $

(?<!hello\s)\w+ Matches word NOT after 'hello '

Notes:

Assertion - matches only if NOT preceded by the pattern

`Email`

Common Patterns

Match email addresses

Pattern:

[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}

Examples:

[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,} Basic email pattern

\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b Email with word boundaries

Notes:

Basic email validation - not RFC compliant but covers most cases

`URL`

Common Patterns

Match URLs

Pattern:

https?://[\w\-]+(\.[\w\-]+)+([\w\-\.,@?^=%&:/~\+#]*[\w\-\@?^=%&/~\+#])?

Examples:

https?://\w+\.\w+ Simple URL pattern

https?://[\w\-]+(\.[\w\-]+)+ More robust URL pattern

Notes:

Matches HTTP and HTTPS URLs

`Phone Number`

Common Patterns

Match phone numbers

Pattern:

$?\d{3}$?[\s\-]?\d{3}[\s\-]?\d{4}

Examples:

\d{3}-\d{3}-\d{4} Format: 123-456-7890

$\d{3}$\s\d{3}-\d{4} Format: (123) 456-7890

$?\d{3}$?[\s\-]?\d{3}[\s\-]?\d{4} Flexible US phone format

Notes:

US phone number formats

`IP Address`

Common Patterns

Match IPv4 addresses

Pattern:

\b(?:[0-9]{1,3}\.){3}[0-9]{1,3}\b

Examples:

\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3} Simple IP pattern

\b(?:[0-9]{1,3}\.){3}[0-9]{1,3}\b IP with word boundaries

\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b Valid IP range (0-255)

Notes:

Basic IP pattern - doesn't validate ranges

`Date`

Common Patterns

Match date formats

Pattern:

\d{1,2}/\d{1,2}/\d{4}

Examples:

\d{1,2}/\d{1,2}/\d{4} MM/DD/YYYY or M/D/YYYY

\d{4}-\d{2}-\d{2} YYYY-MM-DD format

\b\d{1,2}[-/]\d{1,2}[-/]\d{4}\b Flexible date with - or /

Notes:

Common date formats - doesn't validate actual dates

`Credit Card`

Common Patterns

Match credit card numbers

Pattern:

\d{4}[\s\-]?\d{4}[\s\-]?\d{4}[\s\-]?\d{4}

Examples:

\d{16} 16 consecutive digits

\d{4}\s\d{4}\s\d{4}\s\d{4} Groups of 4 with spaces

\d{4}[\s\-]?\d{4}[\s\-]?\d{4}[\s\-]?\d{4} Flexible spacing/dashes

Notes:

Basic credit card format - doesn't validate card numbers

`Hex Color`

Common Patterns

Match hexadecimal color codes

Pattern:

#[0-9A-Fa-f]{6}|#[0-9A-Fa-f]{3}

Examples:

#[0-9A-Fa-f]{6} 6-digit hex color: #FF0000

#[0-9A-Fa-f]{3} 3-digit hex color: #F00

#[0-9A-Fa-f]{6}|#[0-9A-Fa-f]{3} Both 3 and 6 digit hex colors

Notes:

Hexadecimal color codes with #

`i`

Flags

Case insensitive matching

Pattern:

/pattern/i

Examples:

/hello/i Matches 'hello', 'Hello', 'HELLO', etc.

/[a-z]+/i Matches letters regardless of case

/test/i Matches 'test', 'Test', 'TEST', etc.

Notes:

Ignores case when matching

`g`

Flags

Global matching (find all matches)

Pattern:

/pattern/g

Examples:

/\d+/g Finds all numbers in text

/cat/g Finds all occurrences of 'cat'

/[aeiou]/g Finds all vowels

Notes:

Without 'g', only first match is returned

`m`

Flags

Multiline mode (^ and $ match line breaks)

Pattern:

/pattern/m

Examples:

/^\w+/m Matches word at start of each line

/\w+$/m Matches word at end of each line

/^#.+$/m Matches lines starting with #

Notes:

Makes ^ and $ match start/end of lines, not just string

`s`

Flags

Dot matches newline characters

Pattern:

/pattern/s

Examples:

/.*/ vs /.*/s With 's', dot matches newlines too

/<.*>/s Matches tags across multiple lines

Notes:

Makes . match newline characters (\n)

Regex Pro Tips

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Use our interactive regex tester to validate and experiment with patterns in real-time.

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Common Workflow

Start with literal text: hello
Add character classes: [a-z]
Use quantifiers: +, *, ?
Add anchors if needed: ^, $
Test with different inputs
Refine and optimize

Best Practices

Keep patterns simple and readable
Use (?:) for non-capturing groups
Escape special characters with \
Test edge cases and empty strings
Consider performance for large datasets
Document complex patterns with comments

Quick Reference

Basics:
. any char
\ escape
| or

Quantifiers:
* 0 or more
+ 1 or more
? 0 or 1

Character Classes:
\d digit
\w word char
\s whitespace

Anchors:
^ start
$ end
\b word boundary