Stream::WriteAsync Method (array<Byte>^, Int32, Int32, CancellationToken)
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.
Assembly: mscorlib (in mscorlib.dll)
public: [ComVisibleAttribute(false)] [HostProtectionAttribute(SecurityAction::LinkDemand, ExternalThreading = true)] virtual Task^ WriteAsync( array<unsigned char>^ buffer, int offset, int count, CancellationToken cancellationToken )
Parameters
- buffer
-
Type:
array<System::Byte>^
The buffer to write data from.
- offset
-
Type:
System::Int32
The zero-based byte offset in buffer from which to begin copying bytes to the stream.
- count
-
Type:
System::Int32
The maximum number of bytes to write.
- cancellationToken
-
Type:
System.Threading::CancellationToken
The token to monitor for cancellation requests. The default value is None.
Return Value
Type: System.Threading.Tasks::Task^A task that represents the asynchronous write operation.
| 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 writing. |
| ObjectDisposedException | The stream has been disposed. |
| InvalidOperationException | The stream is currently in use by a previous write operation. |
The WriteAsync 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#.
Use the CanWrite property to determine whether the current instance supports writing.
If the operation is canceled before it completes, the returned task contains the Canceled value for the Status property.
For an example, see the WriteAsync(array<Byte>^, Int32, Int32) overload.
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