Global _b
boost::xpressive::_b — Word boundary assertion. 
 
Synopsis
Description
'_b' matches the zero-width sub-sequence at the beginning or the end of a word. It is equivalent to (bow | eow). The regex traits are used to determine what constitutes a word character. To match a non-word boundary, use ~_b.
| ![[Note]](../../../../doc/src/images/note.png) | Note | 
| _b is like \b in perl. ~_b is like \B in perl.  |