Begins an asynchronous write.
Assembly: mscorlib (in mscorlib.dll)
public override function BeginWrite( array : byte, offset : int, numBytes : int, userCallback : AsyncCallback, stateObject : Object ) : IAsyncResult
- Type: System.Byte
The buffer containing data to write to the current stream.
- Type: System.Int32
The zero-based byte offset in array at which to begin copying bytes to the current stream.
- Type: System.Int32
The maximum number of bytes to write.
- Type: System.AsyncCallback
The method to be called when the asynchronous write operation is completed.
- Type: System.Object
A user-provided object that distinguishes this particular asynchronous write request from other requests.
Return ValueType: System.IAsyncResult
An object that references the asynchronous write.
array length minus offset is less than numBytes.
array is a null reference (Nothing in Visual Basic).
offset or numBytes is negative.
The stream does not support writing.
The stream is closed.
An I/O error occurs.
The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: ExternalThreading. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.
This method overrides BeginWrite.
FileStream provides two different modes of operation: synchronous I/O and asynchronous I/O. While either can be used, the underlying operating system resources might allow access in only one of these modes. By default, FileStream opens the operating system handle synchronously. In Windows, this slows down asynchronous methods. If asynchronous methods are used, use the FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean) constructor.
If a stream is closed or you pass an invalid argument, exceptions are thrown immediately from . Errors that occur during an asynchronous write request, such as a disk failure during the IO request, occur on the thread pool thread and become visible upon a call to EndWrite.
Multiple simultaneous asynchronous requests render the request completion order uncertain.
Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows CE Platform Note: In .NET Compact Framework applications, this method is supported, but it is reserved for future use. Using this method will raise a NotSupportedException until it becomes available in a future release.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.