Regex Cheatsheet

Complete regex reference with patterns, character classes, quantifiers, and more. Search and copy patterns easily.

Search Patterns

Character Classes

.Any character except newlinea.c → abc, aXc

\dDigit (0-9)\d{3} → 123

\DNon-digit\D+ → abc

\wWord character (a-z, A-Z, 0-9, _)\w+ → hello_123

\WNon-word character\W → @, #, !

\sWhitespace (space, tab, newline)a\sb → a b

\SNon-whitespace\S+ → hello

[abc]Any of a, b, or c[aeiou] → vowels

[^abc]Not a, b, or c[^0-9] → non-digits

[a-z]Range a to z[A-Za-z] → letters

Anchors

^Start of string/line^Hello → Hello...

$End of string/lineworld$ → ...world

\bWord boundary\bcat\b → cat (not cats)

\BNon-word boundary\Bcat → bobcat

Quantifiers

*0 or morea* → '', a, aa, aaa

+1 or morea+ → a, aa, aaa

?0 or 1 (optional)colou?r → color, colour

{n}Exactly n times\d{4} → 2024

{n,}n or more times\d{2,} → 12, 123, 1234

{n,m}Between n and m times\d{2,4} → 12, 123, 1234

*?0 or more (lazy)a*? → minimal match

+?1 or more (lazy)<.+?> → <b> (not <b>...</b>)

Groups & References

(abc)Capturing group(\d+) → captures digits

(?:abc)Non-capturing group(?:ab)+ → abab

(?<name>abc)Named capturing group(?<year>\d{4})

\1Backreference to group 1(\w)\1 → aa, bb

(a|b)Alternation (a or b)(cat|dog) → cat or dog

Lookahead & Lookbehind

(?=abc)Positive lookahead\d(?=px) → 5 in '5px'

(?!abc)Negative lookahead\d(?!px) → 5 in '5em'

(?<=abc)Positive lookbehind(?<=\$)\d+ → 100 in '$100'

(?<!abc)Negative lookbehind(?<!\$)\d+ → 100 in '€100'

Flags

gGlobal (find all matches)/a/g → all 'a' matches

iCase insensitive/abc/i → ABC, abc, Abc

mMultiline (^ and $ match line breaks)/^line/m

sDotall (. matches newlines)/a.b/s → a\nb

uUnicode support/\u{1F600}/u → emoji

Common Patterns

^[\w.-]+@[\w.-]+\.\w{2,}$Email (basic)user@example.com

^https?://[\w.-]+(?:/[\w.-]*)*$URL (basic)https://example.com/path

^\d{4}-\d{2}-\d{2}$Date (YYYY-MM-DD)2024-01-15

^\+?[\d\s-]{10,}$Phone number (basic)+1 555-123-4567

^#?([0-9A-Fa-f]{3}|[0-9A-Fa-f]{6})$Hex color#FF5733, #F00

^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$IPv4 address (basic)192.168.1.1

Regular Expressions - Technical Details

Regular expressions (regex) are patterns for matching text. They're used in search, validation, parsing, and text manipulation across programming languages and tools.

Command-line Alternative

// Common patterns\n\\d+       Match digits\n\\w+       Match word chars\n^...$     Start/end anchors\n(a|b)     Alternation\n(?=...)   Positive lookahead