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Regular Expression Reference: Quantifiers

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
Greedy quantifier	`?` (question mark)	Makes the preceding item optional. Greedy, so the optional item is included in the match if possible.	`abc?` matches `abc` or `ab`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA extended egrep awk	ECMA extended egrep awk	YES	no	YES	no	YES	YES	YES	YES
Greedy quantifier	`\?`	Makes the preceding item optional. Greedy, so the optional item is included in the match if possible.	`abc\?` matches `abc` or `ab`	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	YES	no	no	no	no
Lazy quantifier	`??`	Makes the preceding item optional. Lazy, so the optional item is excluded in the match if possible.	`abc??` matches `ab` or `abc`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA	ECMA	YES	no	no	no	no	10gR2	no	YES
Possessive quantifier	`?+`	Makes the preceding item optional. Possessive, so if the optional item can be matched, then the quantifier won’t give up its match even if the remainder of the regex fails.	`abc?+c` matches `abcc` but not `abc`	YES	no	YES	5.10	YES	YES	YES	YES	YES	no	no	no	no	1.9	no	ECMA 1.42–1.85	no	no	no	no	no	no	no	no
Greedy quantifier	`*` (star)	Repeats the previous item zero or more times. Greedy, so as many items as possible will be matched before trying permutations with less matches of the preceding item, up to the point where the preceding item is not matched at all.	`".*"` matches `"def" "ghi"` in `abc "def" "ghi" jkl`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
Lazy quantifier	`*?`	Repeats the previous item zero or more times. Lazy, so the engine first attempts to skip the previous item, before trying permutations with ever increasing matches of the preceding item.	`".*?"` matches `"def"` and `"ghi"` in `abc "def" "ghi" jkl`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA	ECMA	YES	no	no	no	no	10gR2	no	YES
Possessive quantifier	`*+`	Repeats the previous item zero or more times. Possessive, so as many items as possible will be matched, without trying any permutations with less matches even if the remainder of the regex fails.	`".*+"` can never match anything	YES	no	YES	5.10	YES	YES	YES	YES	YES	no	no	no	no	1.9	no	ECMA 1.42–1.85	no	no	no	no	no	no	no	no
Greedy quantifier	`+` (plus)	Repeats the previous item once or more. Greedy, so as many items as possible will be matched before trying permutations with less matches of the preceding item, up to the point where the preceding item is matched only once.	`".+"` matches `"def" "ghi"` in `abc "def" "ghi" jkl`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA extended egrep awk	ECMA extended egrep awk	YES	no	YES	no	YES	YES	YES	YES
Greedy quantifier	`\+`	Repeats the previous item once or more. Greedy, so as many items as possible will be matched before trying permutations with less matches of the preceding item, up to the point where the preceding item is matched only once.	`".\+"` matches `"def" "ghi"` in `abc "def" "ghi" jkl`	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	YES	no	no	no	no
Lazy quantifier	`+?`	Repeats the previous item once or more. Lazy, so the engine first matches the previous item only once, before trying permutations with ever increasing matches of the preceding item.	`".+?"` matches `"def"` and `"ghi"` in `abc "def" "ghi" jkl`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA	ECMA	YES	no	no	no	no	10gR2	no	YES
Possessive quantifier	`++`	Repeats the previous item once or more. Possessive, so as many items as possible will be matched, without trying any permutations with less matches even if the remainder of the regex fails.	`".++"` can never match anything	YES	no	YES	5.10	YES	YES	YES	YES	YES	no	no	no	no	1.9	no	ECMA 1.42–1.85	no	no	no	no	no	no	no	no
Fixed quantifier	`{n}` where n is an integer >= 1	Repeats the previous item exactly n times.	`a{3}` matches `aaa`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA extended egrep awk	ECMA extended egrep awk	YES	no	YES	no	YES	YES	YES	YES
Greedy quantifier	`{n,m}` where n >= 0 and m >= n	Repeats the previous item between n and m times. Greedy, so repeating m times is tried before reducing the repetition to n times.	`a{2,4}` matches `aaaa`, `aaa` or `aa`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA extended egrep awk	ECMA extended egrep awk	YES	no	YES	no	YES	YES	YES	YES
Greedy quantifier	`{n,}` where n >= 0	Repeats the previous item at least n times. Greedy, so as many items as possible will be matched before trying permutations with less matches of the preceding item, up to the point where the preceding item is matched only n times.	`a{2,}` matches `aaaaa` in `aaaaa`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA extended egrep awk	ECMA extended egrep awk	YES	no	YES	no	YES	YES	YES	YES
Greedy quantifier	`{,m}` where m >= 1	Repeats the previous item between zero and m times. Greedy, so repeating m times is tried before reducing the repetition to zero times.	`a{,4}` matches `aaaa`, `aaa`, `aa`, `a`, or the empty string	V2	no	no	no	no	no	no	no	no	no	no	no	YES	1.9	no	no	no	no	no	no	YES	no	no	no
Fixed quantifier	`\{n\}` where n is an integer >= 1	Repeats the previous item exactly n times.	`a\{3\}` matches `aaa`	no	no	no	no	no	no	no	no	no	no	no	no	no	no	basic grep	basic grep	no	YES	no	YES	no	no	no	no
Greedy quantifier	`\{n,m\}` where n >= 0 and m >= n	Repeats the previous item between n and m times. Greedy, so repeating m times is tried before reducing the repetition to n times.	`a\{2,4\}` matches `aaaa`, `aaa` or `aa`	no	no	no	no	no	no	no	no	no	no	no	no	no	no	basic grep	basic grep	no	YES	no	YES	no	no	no	no
Greedy quantifier	`\{n,\}` where n >= 0	Repeats the previous item at least n times. Greedy, so as many items as possible will be matched before trying permutations with less matches of the preceding item, up to the point where the preceding item is matched only n times.	`a\{2,\}` matches `aaaaa` in `aaaaa`	no	no	no	no	no	no	no	no	no	no	no	no	no	no	basic grep	basic grep	no	YES	no	YES	no	no	no	no
Greedy quantifier	`\{,m\}` where m >= 1	Repeats the previous item between zero and m times. Greedy, so repeating m times is tried before reducing the repetition to zero times.	`a\{,4\}` matches `aaaa`, `aaa`, `aa`, `a`, or the empty string	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	YES	no	no	no	no
Lazy quantifier	`{n,m}?` where n >= 0 and m >= n	Repeats the previous item between n and m times. Lazy, so repeating n times is tried before increasing the repetition to m times.	`a{2,4}?` matches `aa`, `aaa` or `aaaa`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA	ECMA	YES	no	no	no	no	10gR2	no	YES
Lazy quantifier	`{n,}?` where n >= 0	Repeats the previous item n or more times. Lazy, so the engine first matches the previous item n times, before trying permutations with ever increasing matches of the preceding item.	`a{2,}?` matches `aa` in `aaaaa`	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	ECMA	ECMA	YES	no	no	no	no	10gR2	no	YES
Lazy quantifier	`{,m}?` where m >= 1	Repeats the previous item between zero and m times. Lazy, so repeating zero times is tried before increasing the repetition to m times.	`a{,4}?` matches the empty string, `a`, `aa`, `aaa` or `aaaa`	V2	no	no	no	no	no	no	no	no	no	no	no	YES	1.9	no	no	no	no	no	no	no	no	no	no
Possessive quantifier	`{n,m}+` where n >= 0 and m >= n	Repeats the previous item between n and m times. Possessive, so as many items as possible up to m will be matched, without trying any permutations with less matches even if the remainder of the regex fails.	`a{2,4}+a` matches `aaaaa` but not `aaaa`	YES	no	YES	5.10	YES	YES	YES	YES	YES	no	no	no	no	no	no	ECMA 1.42–1.85	no	no	no	no	no	no	no	no
Possessive quantifier	`{n,}+` where n >= 0	Repeats the previous item n or more times. Possessive, so as many items as possible will be matched, without trying any permutations with less matches even if the remainder of the regex fails.	`a{2,}+a` never matches anything	YES	no	YES	5.10	YES	YES	YES	YES	YES	no	no	no	no	no	no	ECMA 1.42–1.85	no	no	no	no	no	no	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