Global cntrl
boost::xpressive::cntrl — Matches a control character. 
 
Synopsis
Description
The regex traits are used to determine which characters are control characters. To match any character that is not a control character, use ~cntrl.
| ![[Note]](../../../../doc/src/images/note.png) | Note | 
| cntrl is equivalent to /[[:cntrl:]]/ in perl. ~cntrl is equivalent to /[[:^cntrl:]]/ in perl.  |