Write some data to the handle at the specified offset.
template< typename ConstBufferSequence> std::size_t write_some_at( uint64_t offset, const ConstBufferSequence & buffers, boost::system::error_code & ec);
This function is used to write data to the random-access handle. The function call will block until one or more bytes of the data has been written successfully, or until an error occurs.
The offset at which the data will be written.
One or more data buffers to be written to the handle.
Set to indicate what error occurred, if any.
The number of bytes written. Returns 0 if an error occurred.
The write_some operation may not write all of the data to the file. Consider
write_at function if you need
to ensure that all data is written before the blocking operation completes.