boost::xpressive::alpha — Matches an alphabetic character.
// In header: <boost/xpressive/regex_primitives.hpp> unspecified alpha;
The regex traits are used to determine which characters are alphabetic. To match any character that is not alphabetic, use ~alpha.
alpha is equivalent to /[[:alpha:]]/ in perl. ~alpha is equivalent to /[[:^alpha:]]/ in perl.
![[Note]](../../../../doc/src/images/note.png)