Boost C++ Libraries

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

Subtraction operator.

buffers_iterator operator-(
    const buffers_iterator & iter,
    std::ptrdiff_t difference);

Header: boost/asio/buffers_iterator.hpp

Convenience header: boost/asio.hpp