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Regular Expression Reference: Character Classes

Feature	Syntax	Description	Example	JGsoft	.NET	Java	Perl	PCRE	PCRE2	PHP	Delphi	R	JavaScript	VBScript	XRegExp	Python	Ruby	std::regex	Boost	Tcl ARE	POSIX BRE	POSIX ERE	GNU BRE	GNU ERE	Oracle	XML	XPath
Character class	`[`	When used outside a character class, `[` begins a character class. Inside a character class, different rules apply. Unless otherwise noted, the syntax on this page is only valid inside character classes, while the syntax on all other reference pages is not valid inside character classes.		YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
Literal character	Any character except `^-]\`	All characters except the listed special characters are literal characters that add themselves to the character class.	`[abc]` matches `a`, `b` or `c`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
Backslash escapes a metacharacter	`\` (backslash) followed by any of `^-]\`	A backslash escapes special characters to suppress their special meaning.	`[\^\]]` matches `^` or `]`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA	ECMA awk	YES	no	no	no	no	no	YES	YES
Literal backslash	`\`	A backslash is a literal character that adds a backslash to the character class.	`[\]` matches `\`	no	no	no	no	no	no	no	no	no	no	no	no	no	no	basic extended grep egrep awk	basic extended grep egrep	no	YES	YES	YES	YES	YES	no	no
Range	`-` (hyphen) between two tokens that each specify a single character.	Adds a range of characters to the character class.	`[a-zA-Z0-9]` matches any ASCII letter or digit	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
Negated character class	`^` (caret) immediately after the opening `[`	Negates the character class, causing it to match a single character not listed in the character class.	`[^a-d]` matches `x` (any character except a, b, c or d)	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
Literal opening bracket	`[`	An opening square bracket is a literal character that adds an opening square bracket to the character class.	`[ab[cd]ef]` matches `aef]`, `bef]`, `[ef]`, `cef]`, and `def]`	YES	YES	no	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	no	YES	YES	YES	YES	YES	YES	YES	YES	no	no
Nested character class	`[`	An opening square bracket inside a character class begins a nested character class.	`[ab[cd]ef]` is the same as `[abcdef]` and matches any letter between `a` and `f`.	no	no	YES	no	no	no	no	no	no	no	no	no	no	1.9	no	no	no	no	no	no	no	no	no	no
Character class subtraction	`[base-[subtract]]`	Removes all characters in the “subtract” class from the “base” class.	`[a-z-[aeiuo]]` matches a single letter that is not a vowel.	YES	2.0–8.0	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	YES	YES
Character class intersection	`[base&&[intersect]]`	Reduces the character class to the characters present in both “base” and “intersect”.	`[a-z&&[^aeiuo]]` matches a single letter that is not a vowel.	V2	no	YES	no	no	no	no	no	no	no	no	no	no	1.9	no	no	no	no	no	no	no	no	no	no
Character class intersection	`[base&&intersect]`	Reduces the character class to the characters present in both “base” and “intersect”.	`[\p{Nd}&&\p{InThai}]` matches a single Thai digit.	no	no	YES	no	no	no	no	no	no	no	no	no	no	1.9	no	no	no	no	no	no	no	no	no	no
Character escape	`\n`, `\r` and `\t`	Add an LF character, a CR character, or a tab character to the character class, respectively.	`[\n\r\t]` a line feed, a carriage return, or a tab.	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA awk	ECMA awk	YES	string	string	string	string	no	YES	YES
Character escape	`\a`	Add the “alert” or “bell” control character (ASCII 0x07) to the character class.	`[\a\t]` matches a bell or a tab character.	YES	YES	YES	YES	YES	YES	YES	YES	YES	no	no	no	YES	YES	awk	ECMA awk	YES	no	no	no	no	no	no	no
Character escape	`\b`	Add the “backspace” control character (ASCII 0x08) to the character class.	`[\b\t]` matches a backspace or a tab character.	YES	YES	no	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA VC’12–VC’15 awk VC’08–VC’22	ECMA awk	YES	no	no	no	no	no	YES	YES
Character escape	`\B`	Add a backslash to the character class.	`[\B]` matches `\`	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	YES	no	no	no	no	no	no	no
Character escape	`\e`	Add the “escape” control character (ASCII 0x1B) to the character class.	`[\e\t]` matches an escape or a tab character.	YES	YES	YES	YES	YES	YES	YES	YES	YES	no	no	no	no	YES	no	ECMA awk	YES	no	no	no	no	no	no	no
Character escape	`\f`	Add the “form feed” control character (ASCII 0x0C) to the character class.	`[\f\t]` matches a form feed or a tab character.	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA awk	ECMA awk	YES	no	no	no	no	no	no	no
Character escape	`\v`	Add the “vertical tab” control character (ASCII 0x0B) to the character class, without adding any other vertical whitespace.	`[\v\t]` matches a vertical tab or a tab character.	V1 only	YES	4–7	no	no	no	no	no	no	YES	YES	YES	YES	YES	ECMA awk	ECMA awk	YES	no	no	no	no	no	no	no
POSIX class	`[:alpha:]`	Matches one character from a POSIX character class. Can only be used in a bracket expression.	`[[:digit:][:lower:]]` matches one of `0` through `9` or `a` through `z`	ASCII	no	no	Unicode	ASCII	ASCII	5.3.4 Unicode 5.0.0 code page	ASCII	ASCII	no	no	no	no	1.9 Unicode 1.8 ASCII	Unicode	Unicode	Unicode	ASCII	ASCII	ASCII	ASCII	Unicode	no	no
POSIX class	`[:^alpha:]`	Matches one character that is not part of a specific POSIX character class. Can only be used in a bracket expression.	`[5[:^digit:]]` matches the digit `5` or any other character that is not a digit.	no	no	no	YES	YES	YES	YES	YES	YES	no	no	no	3.7–3.10 error	1.9	error	YES	error	error	error	error	error	error	no	no
POSIX shorthand class	`[:d:]`, `[:s:]`, `[:w:]`	Matches one character from the POSIX character classes “digit”, “space”, or “word”. Can only be used in a bracket expression.	`[[:s:][:d:]]` matches a space, a tab, a line break, or one of `0` through `9`	V2 ASCII	no	no	no	no	no	no	no	no	no	no	no	no	no	Unicode	Unicode	no	no	no	no	no	no	no	no
POSIX shorthand class	`[:l:]` and `[:u:]`	Matches one character from the POSIX character classes “lower” or “upper”. Can only be used in a bracket expression.	`[[:u:]][[:l:]]` matches `Aa` but not `aA`.	V2 ASCII	no	no	no	no	no	no	no	no	no	no	no	no	no	no	Unicode	no	no	no	no	no	no	no	no
POSIX shorthand class	`[:h:]`	Matches one character from the POSIX character classes “blank”. Can only be used in a bracket expression.	`[[:h:]]` matches a space.	V2 ASCII	no	no	no	no	no	no	no	no	no	no	no	no	no	no	1.42–1.85 Unicode	no	no	no	no	no	no	no	no
POSIX shorthand class	`[:V:]`	Matches a vertical whitespace character. Can only be used in a bracket expression.	`[[:v:]]` match any single vertical whitespace character.	V2 ASCII	no	no	no	no	no	no	no	no	no	no	no	no	no	no	1.42–1.85 Unicode	no	no	no	no	no	no	no	no
POSIX class	Any supported `\p{…}` syntax	`\p{…}` syntax can be used inside character classes.	`[\p{Digit}\p{Lower}]` matches one of `0` through `9` or `a` through `z`	YES	n/a	9	YES	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	1.9	n/a	extended egrep	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a
POSIX class	`\p{Alpha}`	Matches one character from a POSIX character class.	`\p{Digit}` matches any single digit.	Unicode	no	ASCII	Unicode	no	no	no	no	no	no	no	no	no	1.9 Unicode	no	ECMA extended egrep awk Unicode	no	no	no	no	no	no	no	no
POSIX class	`\p{IsAlpha}`	Matches one character from a POSIX character class.	`\p{IsDigit}` matches any single digit.	Unicode	no	9 Unicode 4 ASCII	Unicode	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no
POSIX collation sequence	`[.span-ll.]`	Matches a POSIX collation sequence. Can only be used in a bracket expression.	`[[.span-ll.]]` matches `ll` in the Spanish locale	error	no	no	error	error	error	error	error	error	no	no	no	3.7–3.10 error	1.8 only error	fail	YES	YES	YES	YES	YES	YES	YES	no	no
POSIX character equivalence	`[=x=]`	Matches a POSIX character equivalence. Can only be used in a bracket expression.	`[[=e=]]` matches `e`, `é`, `è` and `ê` in the French locale	error	no	no	error	error	error	error	error	error	no	no	no	3.7–3.10 error	1.8 only error	YES	YES	YES	YES	YES	YES	YES	YES	no	no
Feature	Syntax	Description	Example	JGsoft	.NET	Java	Perl	PCRE	PCRE2	PHP	Delphi	R	JavaScript	VBScript	XRegExp	Python	Ruby	std::regex	Boost	Tcl ARE	POSIX BRE	POSIX ERE	GNU BRE	GNU ERE	Oracle	XML	XPath