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##### basic_stream_socket::async_send (2 of 2 overloads)

Start an asynchronous send.

    template<
        typename ConstBufferSequence,
        typename WriteHandler>
    DEDUCED async_send(
        const ConstBufferSequence & buffers,
        socket_base::message_flags flags,
        WriteHandler && handler);

This function is used to asynchronously send data on the stream socket. The function call always returns immediately.

###### Parameters

buffers

  One or more data buffers to be sent on the socket. Although the buffers object may be copied as necessary, ownership of the underlying memory blocks is retained by the caller, which must guarantee that they remain valid until the handler is called.

flags

  Flags specifying how the send call is to be made.

handler

  The handler to be called when the send operation completes. Copies will be made of the handler as required. The function signature of the handler must be:

      void handler(
        const boost::system::error_code& error, // Result of operation.
        std::size_t bytes_transferred           // Number of bytes sent.
      );

  Regardless of whether the asynchronous operation completes immediately or not, the handler will not be invoked from within this function. Invocation of the handler will be performed in a manner equivalent to using `boost::asio::io_context::post()`.

###### Remarks

The send operation may not transmit all of the data to the peer. Consider using the `async_write` function if you need to ensure that all data is written before the asynchronous operation completes.

###### Example

To send a single data buffer use the `buffer` function as follows:

    socket.async_send(boost::asio::buffer(data, size), 0, handler);

See the `buffer` documentation for information on sending multiple buffers in one go, and how to use it with arrays, boost::array or std::vector.