Gets a value indicating whether the FileStream was opened asynchronously or synchronously.
Assembly: mscorlib (in mscorlib.dll)
The IsAsync property detects whether the FileStream handle was opened asynchronously, enabling your code to use the Handle property correctly. In Win32, IsAsync being true means the handle was opened for overlapped I/O, and thus requires different parameters to ReadFile and WriteFile.
You specify this value when you create an instance of the FileStream class using a constructor that has an isAsync, useAsync, or options parameter. When the property is true, the stream utilizes overlapped I/O to perform file operations asynchronously. However, the property does not have to be true to call the ReadAsync, WriteAsync, or CopyToAsync method. When the property is false and you call the asynchronous read and write operations, the UI thread is still not blocked, but the actual I/O operation is performed synchronously.
Windows 98, Windows Millennium Edition Platform Note: These operating systems do not support asynchronous I/O. If code for these platforms requests that files be opened asynchronously, the common language runtime will open them synchronously instead.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)