[/ / Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com) / / Distributed under the Boost Software License, Version 1.0. (See accompanying / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) /] [section:SyncRandomAccessWriteDevice Buffer-oriented synchronous random-access write device requirements] In the table below, `a` denotes a synchronous random-access write device object, `o` denotes an offset of type `boost::uint64_t`, `cb` denotes an object satisfying [link boost_asio.reference.ConstBufferSequence constant buffer sequence] requirements, and `ec` denotes an object of type `error_code`. [table Buffer-oriented synchronous random-access write device requirements [[operation] [type] [semantics, pre/post-conditions]] [ [`a.write_some_at(o, cb);`] [`size_t`] [Equivalent to: `` error_code ec; size_t s = a.write_some(o, cb, ec); if (ec) throw system_error(ec); return s; ``] ] [ [`a.write_some_at(o, cb, ec);`] [`size_t`] [ Writes one or more bytes of data to the device `a` at offset `o`.[br] [br] The constant buffer sequence `cb` specifies memory where the data to be written is located. The `write_some_at` operation shall always write a buffer in the sequence completely before proceeding to the next.[br] [br] If successful, returns the number of bytes written and sets `ec` such that `!ec` is true. If an error occurred, returns `0` and sets `ec` such that `!!ec` is true.[br] [br] If the total size of all buffers in the sequence `cb` is `0`, the function shall return `0` immediately. ] ] ] [endsect]