...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards
...one of the most highly regarded and expertly designed C++ library projects in the world.
boost::xpressive::digit — Matches a digit character.
unspecified digit;
The regex traits are used to determine which characters are digits. To match any character that is not a digit, use ~digit.