Operator/Syntax

Description

Example

Explanation

.

Matches any single character except a newline.

a.b

Matches aab, acb, but not ab or a\nb.

*

Matches 0 or more repetitions of the preceding element.

ab*

Matches a, ab, abb, abbb.

+

Matches 1 or more repetitions of the preceding element.

ab+

Matches ab, abb, abbb, but not a.

?

Matches 0 or 1 repetition of the preceding element.

colou?r

Matches color or colour.

`

`

OR operator (matches either pattern).

`cat

^

Matches the start of a string.

^Hello

Matches Hello only at the beginning of the string.

$

Matches the end of a string.

world$

Matches world only at the end of the string.

[]

Matches any one character in the brackets.

[abc]

Matches a, b, or c.

[^]

Matches any one character not in the brackets.

[^abc]

Matches any character except a, b, or c.

()

Groups expressions. Used for capturing.

(ab)+

Matches ab, abab, ababab. Captures each repetition.

{n}

Matches exactly n repetitions.

a{3}

Matches aaa.

{n,}

Matches n or more repetitions.

a{2,}

Matches aa, aaa, aaaa, etc.

{n,m}

Matches between n and m repetitions.

a{2,4}

Matches aa, aaa, or aaaa.

\

Escapes a special character.

\.

Matches the literal . character.

\d

Matches any digit (0–9).

\d+

Matches 123, 456, etc.

\D

Matches any non-digit.

\D+

Matches abc, @#$, etc.

\w

Matches any word character (letters, digits, underscore).

\w+

Matches hello, word_1, etc.

\W

Matches any non-word character.

\W+

Matches @#$, (space), etc.

\s

Matches any whitespace character.

\s+

Matches spaces, tabs, or newlines.

\S

Matches any non-whitespace character.

\S+

Matches words or symbols, but not spaces.