Replacement String Features Comparison

Characters

Feature Syntax Description Example specRegex .NET std::regex PCRE2 RE2
Backslash A backslash that does not form a token Invalid escapes insert the escaped character literally. \! inserts ! ❌ ❌ ✔ (Opt) ✔ (Opt) ❌
Backslash A backslash that does not form a token A backslash that is not part of a replacement string token is a literal \! inserts \! ✔ ✔ ✔ ✔ ❌
Backslash Trailing backslash Trailing backslash is literal backslash \ at the end inserts \ ✔ ✔ ✔ ✔ ❌
Backslash \\ A backslash escapes itself \\ inserts \ ❌ ❌ ✔ (Opt) ✔ (Opt) ✔
Dollar A dollar that does not form a token A dollar that does not form a token is a literal dollar $! inserts $! ✔ ✔ ✔ ❌ ✔
Dollar Trailing dollar A trailing dollar is a literal dollar $ at the end inserts $ ✔ ✔ ✔ ❌ ✔
Dollar $$ A dollar escapes itself $$ inserts $ ✔ ✔ ✔ ✔ ❌
Dollar \$ A backslash escapes a dollar \$ inserts $ ✔ ✔ ✔ ✔ ❌
Hexadecimal escape \xFF where FF are 2 hexadecimal digits Insert the single-byte character FF ✔ ❌ ✔ ✔ ❌
Character escape \n, \r and \t Insert an LF character, CR character and a tab character respectively \r\n inserts a CRLF line break ✔ ❌ ✔ ✔ ❌
Character escape \a Insert the “alert” or “bell” control character (ASCII 0x07) ✔ ❌ ❌ ✔ ❌
Character escape \b Insert the “backspace” control character (ASCII 0x08) ✔ ❌ ❌ ❌ ❌
Character escape \e Insert the “escape” control character (ASCII 0x1A) ✔ ❌ ❌ ✔ ❌
Character escape \f Insert the “form feed” control character (ASCII 0x0C) ✔ ❌ ❌ ✔ ❌
Character escape \v Insert the “vertical tab” control character (ASCII 0x0B) ✔ ❌ ❌ ❌ ❌
Control character escape \cA through ASCII character ^A through ^Z, equivalent to \x01 through\x1A \cM\cJ inserts a CRLF linebreak ✔ ❌ ❌ ✔ ❌
Control character escape \ca through ASCII character ^A through ^Z, equivalent to \x01 through\x1A \cm\cj inserts a CRLF linebreak ✔ ❌ ❌ ✔ ❌
NULL escape \0 Insert the null character ✔ ❌ ❌ ❌ ❌
Octal escape \o{7777} for any octal number Insert the character with the specified number \o{20254} inserts € ✔ ❌ ❌ ✔ ❌
Octal escape \1 through \7 Insert the character at the specified position in the ASCII table \7 inserts the “bell” character ❌ ❌ ❌ ❌ ❌
Octal escape \10 through \77 Insert the character at the specified position in the ASCII table \77 inserts ? ❌ ❌ ❌ ❌ ❌
Octal escape \100 through \177 Insert the character at the specified position in the ASCII table \100 inserts @ ❌ ❌ ❌ ❌ ❌
Octal escape \200 through \377 Insert the character at the specified position in the active code page \377 inserts ÿ ❌ ❌ ❌ ❌ ❌
Octal escape \400 through \777 Insert the character at the specified position in the active code page \777 inserts ǿ ❌ ❌ ❌ ❌ ❌
Octal escape \01 through \07 Insert the character at the specified position in the ASCII table \07 inserts the “bell” character ❌ ❌ ❌ ❌ ❌
Octal escape \010 through \077 Insert the character at the specified position in the ASCII table \077 inserts ? ❌ ❌ ❌ ❌ ❌
Octal escape \0100 through \0177 Insert the character at the specified position in the ASCII table \0100 inserts @ ❌ ❌ ❌ ❌ ❌
Octal escape \0200 through \0377 Insert the character at the specified position in the active code page \0377 inserts ÿ ❌ ❌ ❌ ❌ ❌

Matched Text and Backreferences

Feature Syntax Description Example specRegex .NET std::regex PCRE2 RE2
Ampersand \& Insert a literal ampersand \& inserts & ❌ ❌ ✔ (Opt) ✔ (Opt) ❌
Whole match \& Insert the whole regex match \& inserts the entire match ✔ ❌ ❌ ❌ ❌
Whole match $& Insert the whole regex match $& inserts the entire match ✔ ✔ ✔ ❌ ❌
Whole match & Insert the whole regex match & inserts the entire match ❌ ❌ ✔ (Opt) ❌ ❌
Whole match \0 Insert the whole regex match \0 inserts the entire match ❌ ❌ ✔ (Opt) ❌ ✔
Whole match $0 Insert the whole regex match $0 inserts the entire match ✔ ✔ ✔ ✔ ❌
Whole match \g<0> Insert the whole regex match ✔ ❌ ❌ ❌ ❌
Whole match $MATCH and ${^MATCH} Insert the whole regex match ✔ ❌ ❌ ❌ ❌
Backreference \1 to \9 Insert the text matched by one of the first 9 capturing groups. \3 inserts capture group 3 ✔ ❌ ✔ (Opt) ❌ ✔
Backreference \10 to \99 Insert the text matched by one of the latter 89 capturing groups. ✔ ❌ ❌ ❌ ❌
Backreference and literal \10 to \99 For <10 groups in regex, treat second digit as a literal \33 may insert <group 3>3 ✔ ❌ ❌ ❌ ✔
Backreference $1 to $9 Insert the text matched by one of the first 9 capturing groups. $3 inserts capture group 3 ✔ ✔ ✔ ✔ ❌
Backreference $10 to $99 Insert the text matched by one of the latter 89 capturing groups. ✔ ✔ ✔ ✔ ❌
Backreference and literal $10 to $99 For <10 groups in regex, treat second digit as a literal $33 may insert <group 3>3 ✔ ✔ (Opt) ❌ ❌ ❌
Backreference ${1} to ${99} Insert the text matched by a numbered capturing group ${3} inserts group 3 ✔ ✔ ❌ ✔ ❌
Backreference \g<1> to \g<99> Insert the text matched by a numbered capturing group \g<3> inserts group 3 ✔ ❌ ❌ ❌ ❌
Named Backreference ${name} Insert the text matched by named group name ${foo} inserts group foo ✔ ✔ ❌ ✔ ❌
Named Backreference $+{name} Insert the text matched by named group name ${foo} inserts group foo ✔ ❌ ❌ ❌ ❌
Named Backreference $name Insert the text matched by named group name $foo inserts group foo ❌ ❌ ❌ ✔ ❌
Named Backreference \g<name> Insert the text matched by named group name \g<foo> inserts group foo ❌ ❌ ❌ ❌ ❌
Invalid backreference Any backref with nonexistent name/number An out-of-bounds backreference is the empty string. ✔ ❌ ✔ ❌ ❌
Invalid backreference Any backref with nonexistent name/number An out-of-bounds backreference is a literal ❌ ✔ ❌ ❌ ❌
Nonparticipating backreference Any backreference with to nonparticipant A non-participating backreference is the empty string ✔ ✔ ✔ ❌ ✔
Last backreference \+ Inserts the highest-numbered participating group ❌ ❌ ❌ ❌ ❌
Last backreference \+ Inserts the highest-numbered group, regardless of participation ❌ ❌ ❌ ❌ ❌
Last backreference $+ Inserts the highest-numbered participating group ❌ ❌ ❌ ❌ ❌
Last backreference $+ Inserts the highest-numbered group, regardless of participation ❌ ✔ ❌ ❌ ❌
Last backreference $^N Inserts the highest-numbered participating group ❌ ❌ ❌ ❌ ❌
Last backreference $LAST_SUBMATCH_RESULT, ${^LAST_SUBMATCH_RESULT} Inserts the highest-numbered participating group ❌ ❌ ❌ ❌ ❌
Last backreference $LAST_PAREN_MATCH, ${^LAST_PAREN_MATCH} Inserts the highest-numbered group, regardless of participation ❌ ❌ ❌ ❌ ❌

Context and Case Conversion

Feature Syntax Description Example specRegex .NET std::regex PCRE2 RE2
Match Context \` Insert the part of the subject string to the left of the regex match. ✔ ❌ ❌ ❌ ❌
Match Context $` Insert the part of the subject string to the left of the regex match. ✔ ✔ ✔ ❌ ❌
Match Context $PREMATCH, ${^PREMATCH} Insert the part of the subject string to the left of the regex match. ✔ ❌ ❌ ❌ ❌
Match Context \' Insert the part of the subject string to the right of the regex match. ✔ ❌ ❌ ❌ ❌
Match Context $' Insert the part of the subject string to the right of the regex match. ✔ ❌ ✔ ❌ ❌
Match Context $POSTMATCH, ${^POSTMATCH} Insert the part of the subject string to the right of the regex match. ✔ ❌ ❌ ❌ ❌
Match Context \_ Insert the entire subject string. ✔ ❌ ❌ ❌ ❌
Match Context $_ Insert the entire subject string. ✔ ✔ ❌ ❌ ❌
Case Conversion \U0 to \U99 Insert a numbered group (or whole match), converted to uppercase. ✔ ❌ ❌ ❌ ❌
Case Conversion \L0 to \L99 Insert a numbered group (or whole match), converted to lowercase. ✔ ❌ ❌ ❌ ❌
Case Conversion \F0 to \F99 Convert the first character to uppercase, and the rest to lowercase. ✔ ❌ ❌ ❌ ❌
Case Conversion \I0 to \I99 Insert a numbered group (or whole match), converted to title case. ✔ ❌ ❌ ❌ ❌
Case Conversion \U Everything until the next \E or \L is uppercased ✔ ❌ ❌ ✔ ❌
Case Conversion \L Everything until the next \E or \U is uppercased ✔ ❌ ❌ ✔ ❌
Case Conversion \u The next character is uppercased ❌ ❌ ❌ ✔ ❌
Case Conversion \l The next character is lowercased ❌ ❌ ❌ ✔ ❌