Most of RegEx engines support a good number of predefined character classes. These are kind of shortcuts to the widely used character classes.
These predefined Character classes start with “\” followed by a character.
Here is the list of most common predefined character classes-
|Predefined Character class||Equivalent to||Meaning|
|\S||[^\t\n\f\r\X0B]||Not White space|
|\w||[a-zA-Z0-9_]||Word char (including underscore)|
|\W||[^a-zA-Z0-9_]||Non word char|
|\b||Word boundary (Black space or special character)|
|\B||Non Word boundary|