Updated: July 2009
Most of the important regular expression language operators are unescaped single characters. The escape character \ (a single backslash) signals to the regular expression parser that the character following the backslash is not an operator. For example, the parser treats an asterisk (*) as a repeating quantifier and a backslash followed by an asterisk (\*) as the Unicode character 002A.
The character escapes listed in this table are recognized in regular expressions, but not in replacement patterns.
Escaped character | Description |
|---|
ordinary characters | Characters other than . $ ^ { [ ( | ) * + ? \ match themselves. |
\a | Matches a bell (alarm) \u0007. |
\b | Matches a backspace \u0008 if in a [] character class; otherwise, see the note following this table. |
\t | Matches a tab \u0009. |
\r | Matches a carriage return \u000D. Note that \r is not equivalent to the newline character, \n. |
\v | Matches a vertical tab \u000B. |
\f | Matches a form feed \u000C. |
\n | Matches a new line \u000A. |
\e | Matches an escape \u001B. |
\040 | Matches an ASCII character as octal (up to three digits); numbers with no leading zero are backreferences if they have only one digit or if they correspond to a capturing group number. (For more information, see Backreferences.) For example, the character \040 represents a space. |
\x20 | Matches an ASCII character using hexadecimal representation (exactly two digits). |
\cC | Matches an ASCII control character; for example, \cC is control-C. |
\u0020 | Matches a Unicode character using hexadecimal representation (exactly four digits). .gif) Note:The Perl 5 character escape that is used to specify Unicode is not supported by the .NET Framework. The Perl 5 character escape is of the form \x{####…}, where "####…" is a series of hexadecimal digits. Instead, use the .NET Framework character escape described in this row. |
\ | When followed by a character that is not recognized as an escaped character, matches that character. For example, \* is the same as \x2A. |
| Note: |
|---|
The escaped character \b is a special case. In a regular expression, \b denotes a word boundary (between \w and \W characters) except within a [] character class, where \b refers to the backspace character. |
Other Resources
Date | History | Reason |
|---|
July 2009
| Noted that character escapes are not supported in replacement strings. |
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