.NET Framework Developer's Guide
Character Escapes

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).

NoteNote:
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.

NoteNote:

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.

See Also

Other Resources

Change History

Date

History

Reason

July 2009

Noted that character escapes are not supported in replacement strings.

Customer feedback.

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