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Replacement Strings Reference: Conditionals

Feature	Syntax	Description	Example	JGsoft	Python	JavaScript	VBScript	XRegExp	.NET	Java	ICU	RE2	Perl	PCRE2	PHP	Delphi	R	Ruby	std::regex	Boost	Tcl	Oracle	XPath
Conditional	`?1yes:no` through `?99yes:no`	Conditional referencing a numbered capturing group. Inserts the “yes” part if the group participated or the “no” part if it didn’t.	Replacing all matches of `(y)?\|n` in `yyn!` with `?1yes:no` yields `yesyesno!`	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	all	no	no	no
Conditional	`(?1yes:no)` through `(?99yes:no)`	Conditional referencing a numbered capturing group. Inserts the “yes” part if the group participated or the “no” part if it didn’t.	Replacing all matches of `(y)?\|n` in `yyn!` with `(?1yes:no)` yields `yesyesno!`	V2	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	all	no	no	no
Conditional	`(?10yes:no)` through `(?99yes:no)`	When there are fewer capturing groups than the 2-digit number, treat this as a single-digit conditional with the “yes” part starting with a literal number instead of as an invalid conditional.	Replacing all matches of `(y)?\|n` in `yyn!` with `(?19yes:no)` yields `9yes9yesno!`	V2	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	no	n/a	n/a	n/a
Conditional	`?{1}yes:no` through `?{99}yes:no`	Conditional referencing a numbered capturing group. Inserts the “yes” part if the group participated or the “no” part if it didn’t.	Replacing all matches of `(y)?\|n` in `yyn!` with `?{1}yes:no` yields `yesyesno!`	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	all 1.42	no	no	no
Conditional	`(?{1}yes:no)` through `(?{99}yes:no)`	Conditional referencing a numbered capturing group. Inserts the “yes” part if the group participated or the “no” part if it didn’t.	Replacing all matches of `(y)?\|n` in `yyn!` with `(?{1}yes:no)` yields `yesyesno!`	V2	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	all 1.42	no	no	no
Conditional	`${1:+yes:no}` through `${99:+yes:no}`	Conditional referencing a numbered capturing group. Inserts the “yes” part if the group participated or the “no” part if it didn’t.	Replacing all matches of `(y)?\|n` in `yyn!` with `${1:+yes:no}` yields `yesyesno!`	V2	no	no	no	no	no	no	no	no	no	extended	no	no	no	no	no	no	no	no	no
Conditional	`${1:-no}` through `${99:-no}`	Conditional referencing a numbered capturing group. Inserts the text captured by the group if it participated or the contents of the conditional if it didn’t.	Replacing all matches of `(y)?\|n` in `yyn!` with `${1:-no}` yields `yyno!`	V2	no	no	no	no	no	no	no	no	no	extended	no	no	no	no	no	no	no	no	no
Conditional	Any numbered conditional	A conditional that references the number of a capturing group that does not exist acts as a conditional to a group that never participates.	Replacing all matches of `(y)?\|n` in `yyn!` with `(?9yes:no)` yields `nonono!`	V2 error	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	extended error	n/a	n/a	n/a	n/a	n/a	all	n/a	n/a	n/a
Conditional	`$?{name}yes:no`	Conditional referencing a named capturing group. Inserts the “yes” part if the group participated or the “no” part if it didn’t.	Replacing all matches of `(?'one'y)?\|n` in `yyn!` with `?{one}yes:no` yields `yesyesno!`	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	all 1.42	no	no	no
Conditional	`(?{name}yes:no)`	Conditional referencing a named capturing group. Inserts the “yes” part if the group participated or the “no” part if it didn’t.	Replacing all matches of `(?'one'y)?\|n` in `yyn!` with `(?{one}yes:no)` yields `yesyesno!`	V2	no	no	no	no	no	no	no	no	no	no	no	no	no	no	no	all 1.42	no	no	no
Conditional	`${name:+yes:no}`	Conditional referencing a named capturing group. Inserts the “yes” part if the group participated or the “no” part if it didn’t.	Replacing all matches of `(?'one'y)?\|n` in `yyn!` with `${one:+yes:no}` yields `yesyesno!`	V2	no	no	no	no	no	no	no	no	no	extended	no	no	no	no	no	no	no	no	no
Conditional	`${name:-no}`	Conditional referencing a named capturing group. Inserts the text captured by the group if it participated or the contents of the conditional if it didn’t.	Replacing all matches of `(?'one'y)?\|n` in `yyn!` with `${one:-no}` yields `yyno!`	V2	no	no	no	no	no	no	no	no	no	extended	no	no	no	no	no	no	no	no	no
Conditional	Any named conditional	A conditional that references the name of a capturing group that does not exist is treated as literal text.	Replacing all matches of `(y)?\|n` in `yn!` with `(?{name}yes:no)` yields `?{name}yes:no?{name}yes:no!`	V2 error	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	extended error	n/a	n/a	n/a	n/a	n/a	all 1.42	n/a	n/a	n/a
Control Verb Argument	`$*MARK`	Insert the argument of the last backtracking control verb to be encountered during the matching process.	Replacing `a+(:LEFT)\|c+(:RIGHT)` with `$*MARK` in `abc` yields `LEFTbRIGHT`	no	no	no	no	error	no	error	error	no	error	10.21	no	no	no	no	no	no	no	no	error
Control Verb Argument	`$REGMARK`	Insert the argument of the last backtracking control verb to be encountered during the matching process.	Replacing `a+(:LEFT)\|c+(:RIGHT)` with `$REGMARK` in `abc` yields `LEFTbRIGHT`	no	no	no	no	error	no	error	error	no	YES	error	no	no	no	no	no	no	no	no	error
Feature	Syntax	Description	Example	JGsoft	Python	JavaScript	VBScript	XRegExp	.NET	Java	ICU	RE2	Perl	PCRE2	PHP	Delphi	R	Ruby	std::regex	Boost	Tcl	Oracle	XPath