FileStream.CopyToAsync(Stream, Int32, CancellationToken) Method
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Asynchronously reads the bytes from the current file stream and writes them to another stream, using a specified buffer size and cancellation token.
public:
override System::Threading::Tasks::Task ^ CopyToAsync(System::IO::Stream ^ destination, int bufferSize, System::Threading::CancellationToken cancellationToken);public override System.Threading.Tasks.Task CopyToAsync (System.IO.Stream destination, int bufferSize, System.Threading.CancellationToken cancellationToken);override this.CopyToAsync : System.IO.Stream * int * System.Threading.CancellationToken -> System.Threading.Tasks.TaskPublic Overrides Function CopyToAsync (destination As Stream, bufferSize As Integer, cancellationToken As CancellationToken) As TaskParameters
- destination
- Stream
The stream to which the contents of the current file stream will be copied.
- bufferSize
- Int32
The size, in bytes, of the buffer. This value must be greater than zero.
- cancellationToken
- CancellationToken
The token to monitor for cancellation requests. The default value is None.
Returns
A task that represents the asynchronous copy operation.
Exceptions
The cancellation token was canceled. This exception is stored into the returned task.
Remarks
The CopyToAsync method enables you to perform resource-intensive I/O operations without blocking the main thread. This performance consideration is particularly important in a Windows 8.x Store app or desktop app where a time-consuming stream operation can block the UI thread and make your app appear as if it is not working. The async methods are used in conjunction with the async and await keywords in Visual Basic and C#.
If the operation is canceled before it completes, the returned task contains the TaskStatus.Canceled value for the Task.Status property.
Copying begins at the current position in the current file stream.
For an example of copying between two streams, see the CopyToAsync(Stream) overload.
