| [...] | A single character listed or contained within a listed range. Ranges can be combined with the {+} and {-} operators. For example [a-z]{+}[0-9] is the same as [0-9a-z] and [a-z]{-}[aeiou] is the same as [b-df-hj-np-tv-z]. |
| [^...] | A single character not listed and not contained within a listed range. |
| . | Any character, default [^\n]. |
| \d | Digit character, [0-9]. |
| \D | Non-digit character, [^0-9]. |
| \s | White space character, [ \t\n\r\f\v]. |
| \S | Non-white space character, [^ \t\n\r\f\v]. |
| \w | Word character, [a-zA-Z0-9_]. |
| \W | Non-word character, [^a-zA-Z0-9_]. |