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The backslash character (\) in a regular expression indicates that the character that follows it either is a special character (as shown in the following table), or should be interpreted literally.

PatternDescriptionSampleMatches
\aMatches a bell character, \u0007.\a"\u0007" in "Error!" + '\u0007'
\bIn a character class, matches a backspace, \u0008.[\b]{3,}"\b\b\b\b" in "\b\b\b\b"
\tMatches a tab, \u0009.(\w+)\t"item1\t", "item2\t" in "item1\titem2\t"
\rMatches a carriage return, \u000D. (\r is not equivalent to the newline character, \n.)\r\n(\w+)"\r\nThese" in "\r\nThese are\ntwo lines."
\vMatches a vertical tab, \u000B.[\v]{2,}"\v\v\v" in "\v\v\v"
\fMatches a form feed, \u000C.[\f]{2,}"\f\f\f" in "\f\f\f"
\nMatches a new line, \u000A.\r\n(\w+)"\r\nThese" in "\r\nThese are\ntwo lines."
\eMatches an escape, \u001B.\e"\x001B" in "\x001B"
\ nnnUses octal representation to specify a character (nnn consists of two or three digits).\w\040\w"a b", "c d" in "a bc d"
\x nnUses hexadecimal representation to specify a character (nn consists of exactly two digits).\w\x20\w"a b", "c d" in "a bc d"
\c X or \c xMatches the ASCII control character that is specified by X or x, where X or x is the letter of the control character.\cC "\x0003" in "\x0003" (Ctrl-C)
\u nnnnMatches a Unicode character by using hexadecimal representation (exactly four digits, as represented by nnnn).\w\u0020\w"a b", "c d" in "a bc d"
\When followed by a character that is not recognized as an escaped character in this and other tables in this topic, matches that character. For example, \* is the same as \x2A, and \. is the same as \x2E. This allows the regular expression engine to disambiguate language elements (such as * or ?) and character literals (represented by \* or \?).\d+[\+-x\*]\d+"2+2" and "3*9" in "(2+2) * 3*9"