WindowsRuntimeStreamExtensions.AsStreamForWrite Method (IOutputStream, Int32)

.NET Framework (current version)

Converts an output stream in the Windows Runtime to a managed stream in the .NET for Windows 8.x Store apps using the specified buffer size.

This API is not CLS-compliant. 

Namespace:  System.IO
Assembly:  System.Runtime.WindowsRuntime (in System.Runtime.WindowsRuntime.dll)

public static Stream AsStreamForWrite(
	this IOutputStream windowsRuntimeStream,
	int bufferSize


Type: IOutputStream

The Windows Runtime IOutputStream object to convert.

Type: System.Int32

The size, in bytes, of the buffer. This value cannot be negative, but it can be 0 (zero) to disable buffering.

Return Value

Type: System.IO.Stream
The converted stream.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IOutputStream. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).


windowsRuntimeStream is null.


bufferSize is negative.

You use this method to specify a buffer size when converting the stream. To use the default buffer size of 16,384 bytes, use the AsStreamForWrite(IOutputStream) overload.

In most situations, buffering improves the performance of stream operations. You can disable buffering by setting bufferSize to zero, but you should do this only when you are sure that disabling buffering is appropriate for your situation.

.NET Framework

Supported in: 4.6, 4.5

.NET for Windows Phone apps

Supported in: Windows Phone Silverlight 8