MemoryStream::ReadAsync Method (array<Byte>^, Int32, Int32, CancellationToken)

.NET Framework (current version)

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)

Syntax

C++

public:
[ComVisibleAttribute(false)]
[HostProtectionAttribute(SecurityAction::LinkDemand, ExternalThreading = true)]
virtual Task<int>^ ReadAsync(
	array<unsigned char>^ buffer,
	int offset,
	int count,
	CancellationToken cancellationToken
) override

Parameters

buffer: Type: array<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.

Exceptions

Exception	Condition
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.

Remarks

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.

Version Information

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.5
Portable Class Library
Supported in: portable .NET platforms
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1