Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for an old version of Boost. Click here to view this page for the latest version.

Global _b

boost::xpressive::_b — Word boundary assertion.


// In header: <boost/xpressive/regex_primitives.hpp>

unspecified _b;


'_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.