Using Special-Meaning Characters
\d matches any digit from zero to nine. Its equivalent is [0-9].
\D matches anything but from zero to nine. Its equivalent is [^0-9].
\s matches any white space character (tab, form feed, carriage return, space, and newline characters).
\S matches any character but a white space character.
\w matches any alphanumeric character, including the underscore. Its equivalent is [a-zA-Z0-9_].
\W matches any character but an alphanumeric character, including the underscore. Its equivalent is [^a-zA-Z0-9_].
\b matches on the word boundary.
\B matches not on a word boundary.
\oNN matches octal numbers.
\xNN matches hexadecimal numbers.
\cC matches control characters.
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