| Regular expression character types | ||||
| Character Type | Description | |||
| \d | A digit from 0 to 9 | |||
| \D | A nondigit character | |||
| \w | A word character (an upper- or lowercase letter, a digit, or an underscore (_) | |||
| \W | A no-word character | |||
| \b | A boundary around a word (a text string of word characters) | |||
| \B | the absence of a boundary around a word | |||
| \s | A white space character (a blank space, tab, new line, carriage return, or form feed) | |||
| \S | A non-white space character | |||
| . | any character | |||