Non printing character
There are many useful non printing characters that must be used occasionally. The following table shows the escape sequences used to represent these non printed characters:
| character | meaning |
|---|---|
| \cx | Match byxThe specified control character. For example, \ cm matches a control-m or carriage return.xThe value of must be either A-Z or one of A-Z. Otherwise, C is treated as a literal ‘C’ character. |
| \f | Match a page feed. Equivalent to \ x0c and \ CL. |
| \n | Match a newline character. Equivalent to \ x0a and \ CJ. |
| \r | Match a carriage return. Equivalent to \ x0d and \ cm. |
| \s | Matches any white space characters, including spaces, tabs, page breaks, and so on. Equivalent to [\ f \ n \ R \ t \ v]. |
| \S | Matches any non whitespace characters. Equivalent to [^ \ f \ n \ R \ t \ v]. |
| \t | Match a tab. Equivalent to \ X09 and \ CI. |
| \v | Match a vertical tab. Equivalent to \ x0B and \ CK. |