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

Write the given data to the stream. Returns the number of bytes written, or 0 if an error occurred and the error handler did not throw.

template<
    typename ConstBufferSequence>
std::size_t write_some(
    const ConstBufferSequence & buffers,
    boost::system::error_code & ec);