WriteAsync

Asynchronously writes a sequence of bytes to the current stream, advances the current position within this stream by the number of bytes written, and monitors cancellation requests.

Syntax

public override System.Threading.Tasks.Task WriteAsync (byte[] buffer, int offset, int count, System.Threading.CancellationToken cancellationToken)

Parameters

buffer
The buffer to write data from.
offset
The zero-based byte offset in buffer from which to begin copying bytes to the stream.
count
The maximum number of bytes to write.
cancellationToken
The token to monitor for cancellation requests.

Returns

A task that represents the asynchronous write operation.

Remarks

The FileStream.WriteAsync(Byte[], int, int, System.Threading.CancellationToken) method enables you to perform resource-intensive file operations without blocking the main thread. This performance consideration is particularly important in a win8_appname_long app or desktop_appname 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#.

Use the FileStream.CanWrite property to determine whether the current instance supports reading.

If the operation is canceled before it completes, the returned task contains the System.Threading.Tasks.TaskStatus.Canceled value for the System.Threading.Tasks.Task.Status property. If the handle to the file is disposed, the returned task contains the ObjectDisposedException exception in the System.Threading.Tasks.Task.Exception property.

Requirements

Namespace: System.IO
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 4.0.0.0