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MemoryStream.ReadAsync Method (Byte[], Int32, Int32, CancellationToken)

July 28, 2014

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.

Namespace:  System.IO
Assembly:  mscorlib (in mscorlib.dll)

public override Task<int> ReadAsync(
	byte[] buffer,
	int offset,
	int count,
	CancellationToken cancellationToken
)

Parameters

buffer
Type: System.Byte []
The buffer to write the data into.
offset
Type: System.Int32
The byte offset in buffer at which to begin writing data from the stream.
count
Type: System.Int32
The maximum number of bytes to read.
cancellationToken
Type: System.Threading.CancellationToken
The token to monitor for cancellation requests. The default value is None.

Return Value

Type: System.Threading.Tasks.Task<Int32>
A task that represents the asynchronous read operation. The value of the TResult parameter 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.

ExceptionCondition
ArgumentNullException

buffer is null.

ArgumentOutOfRangeException

offset or count is negative.

ArgumentException

The sum of offset and count is larger than the buffer length.

NotSupportedException

The stream does not support reading.

ObjectDisposedException

The stream has been disposed.

InvalidOperationException

The stream is currently in use by a previous read operation.

If the operation is canceled before it completes, the returned task contains the Canceled value for the Status property.

You can create a cancellation token by creating an instance of the CancellationTokenSource class and passing the Token property as the cancellationToken parameter.

Windows Phone OS

Supported in: 8.1, 8.0

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