BufferedStream.ReadAsync Method (System.IO) (original) (raw)
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Asynchronously reads a sequence of bytes from the current stream, advances the position within the stream by the number of bytes read, and monitors cancellation requests.
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override System::Threading::Tasks::Task<int> ^ ReadAsync(cli::array <System::Byte> ^ buffer, int offset, int count, System::Threading::CancellationToken cancellationToken);public override System.Threading.Tasks.Task<int> ReadAsync(byte[] buffer, int offset, int count, System.Threading.CancellationToken cancellationToken);override this.ReadAsync : byte[] * int * int * System.Threading.CancellationToken -> System.Threading.Tasks.Task<int>Public Overrides Function ReadAsync (buffer As Byte(), offset As Integer, count As Integer, cancellationToken As CancellationToken) As Task(Of Integer)Parameters
buffer
Byte[]
The buffer to write the data into.
offset
The byte offset in buffer at which to begin writing data from the stream.
count
The maximum number of bytes to read.
Returns
A task that represents the asynchronous read operation. The returned task contains the total number of bytes read into the buffer. The result value can be less than the number of bytes requested if the number of bytes currently available is less than the requested number, or it can be 0 (zero) if the end of the stream has been reached.
Exceptions
offset or count is negative.
The sum of offset and count is larger than the buffer length.
The stream does not support reading.
The stream has been disposed.
The stream is currently in use by a previous read operation.
The cancellation token was canceled. This exception is stored into the returned task.
Remarks
You can create a cancellation token by creating an instance of the CancellationTokenSource class and passing the Token property as the cancellationToken parameter.
This method stores in the task it returns all non-usage exceptions that the method's synchronous counterpart can throw. If an exception is stored into the returned task, that exception will be thrown when the task is awaited. Usage exceptions, such as ArgumentException, are still thrown synchronously. For the stored exceptions, see the exceptions thrown by Read(Byte[], Int32, Int32).