Regular Expression Reference: Unicode Boundaries

Feature	Syntax	Description	Example	JGsoft	Python	JavaScript	VBScript	XRegExp	.NET	Java	ICU	RE2	Perl	PCRE	PCRE2	PHP	Delphi	R	Ruby	std::regex	Boost	Tcl	POSIX	GNU	Oracle	XML	XPath
UAX 29 word boundary	`\b` and `\B`	\b matches at a word boundary ÷ and \B matches at a word non-boundary ×ばつ according to Unicode Standard Annex #29.	`(?w)\b.\b` matches `!` because the WB1 and WB2 rules in UAX 29 treat the start and end of the string as a word boundary.	no	no	no	no	no	no	no	option	no	no	no	no	no	no	no	no	no	no	n/a	n/a	no	n/a	n/a	n/a
UAX 29 word boundary	`\b{wb}`	Matches at a word boundary ÷ according to Unicode Standard Annex #29.	`\b{wb}.\b{wb}` matches `!` because the WB1 and WB2 rules in UAX 29 treat the start and end of the string as a word boundary.	no	no	no	no	no	no	no	no	no	5.22	no	no	no	no	no	no	no	no	no	no	no	no	no	no
UAX 29 word non-boundary	`\B{wb}`	Matches at a word non-boundary ×ばつ according to Unicode Standard Annex #29.	`\B{wb}'\B{wb}` matches `'` in `John's` because the WB6 and WB7 rules in UAX 29 treat the positions before and after a hyphen between two letters as a word non-boundary.	no	no	no	no	no	no	no	no	no	5.22	no	no	no	no	no	no	no	no	no	no	no	no	no	no
UAX 29 grapheme boundary	`\b{g}`	Matches at a grapheme boundary ÷ according to Unicode Standard Annex #29.	`\b{g}` matches at the start and the end of the 4 strings `à` (U+0061 U+0300), `คู` (U+0E0F U+0E39), `अः` (U+0905 U+0903), and `ガ` (U+FF76 U+FF9F), but not in the middle of these strings.	no	no	no	no	no	no	9	no	no	5.22	no	no	no	no	no	no	no	no	no	no	no	no	no	no
UAX 29 grapheme non-boundary	`\B{g}`	Matches at a grapheme non-boundary ×ばつ according to Unicode Standard Annex #29.	`\b{g}` matches between the 2 code points in each of the 4 strings `à` (U+0061 U+0300), `คู` (U+0E0F U+0E39), `अः` (U+0905 U+0903), and `ガ` (U+FF76 U+FF9F), but not at the start or end of these strings.	no	no	no	no	no	no	no	no	no	5.22	no	no	no	no	no	no	no	no	no	no	no	no	no	no
UAX 29 grapheme boundary	`\b{gcb}`	Matches at a grapheme boundary ÷ according to Unicode Standard Annex #29.	`\b{gcb}` matches at the start and the end of the 4 strings `à` (U+0061 U+0300), `คู` (U+0E0F U+0E39), `अः` (U+0905 U+0903), and `ガ` (U+FF76 U+FF9F), but not in the middle of these strings.	no	no	no	no	no	no	no	no	no	5.22	no	no	no	no	no	no	no	no	no	no	no	no	no	no
UAX 29 grapheme non-boundary	`\B{gcb}`	Matches at a grapheme non-boundary ×ばつ according to Unicode Standard Annex #29.	`\b{gcb}` matches between the 2 code points in each of the 4 strings `à` (U+0061 U+0300), `คู` (U+0E0F U+0E39), `अः` (U+0905 U+0903), and `ガ` (U+FF76 U+FF9F), but not at the start or end of these strings.	no	no	no	no	no	no	no	no	no	5.22	no	no	no	no	no	no	no	no	no	no	no	no	no	no
UAX 29 sentence boundary	`\b{sb}`	Matches at a sentence boundary ÷ according to Unicode Standard Annex #29.	`\b{sb}.+?\b{sb}` matches `One!` and then `Two!` in `One! Two!`	no	no	no	no	no	no	no	no	no	5.22	no	no	no	no	no	no	no	no	no	no	no	no	no	no
UAX 29 sentence non-boundary	`\B{sb}`	Matches at a sentence non-boundary ×ばつ according to Unicode Standard Annex #29.	no	no	no	no	no	no	no	no	no	5.22	no	no	no	no	no	no	no	no	no	no	no	no	no	no
UAX 14 line boundary	`\b{lb}`	Matches at a line boundary ÷ according to Unicode Standard Annex #14.	`\b{lb}.+?\b{lb}` matches only `Two!` in `One! Two!`	no	no	no	no	no	no	no	no	no	5.24	no	no	no	no	no	no	no	no	no	no	no	no	no	no
UAX 14 line non-boundary	`\B{lb}`	Matches at a line non-boundary ×ばつ according to Unicode Standard Annex #14.	no	no	no	no	no	no	no	no	no	5.24	no	no	no	no	no	no	no	no	no	no	no	no	no	no
Feature	Syntax	Description	Example	JGsoft	Python	JavaScript	VBScript	XRegExp	.NET	Java	ICU	RE2	Perl	PCRE	PCRE2	PHP	Delphi	R	Ruby	std::regex	Boost	Tcl	POSIX	GNU	Oracle	XML	XPath