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Start an asynchronous write.

    typename ConstBufferSequence,
    typename WriteHandler = DEFAULT>
DEDUCED async_write_some(
    const ConstBufferSequence & buffers,
    WriteHandler && handler = DEFAULT);

This function is used to asynchronously write one or more bytes of data to the stream. The function call always returns immediately.



The data to be written to the stream. Although the buffers object may be copied as necessary, ownership of the underlying buffers is retained by the caller, which must guarantee that they remain valid until the handler is called.


The handler to be called when the write operation completes. Copies will be made of the handler as required. The equivalent 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 written.


The async_write_some 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.

Per-Operation Cancellation

This asynchronous operation supports cancellation for the following cancellation_type values:

if they are also supported by the Stream type's async_read_some and async_write_some operations.