Create a File in C# and pass it as an IntPtr to a COM object

I'm working with some COM objects in C#, one of them has a function called SetLogFile that takes a开发者_Go百科n IntPtr. How can I create the file in C# then pass it as an IntPtr to that COM function?

EDIT: The function requires an open file handle: http://msdn.microsoft.com/en-us/library/aa915939.aspx

You're a little vague as to what you have to pass in as the "file"- if you have a FileStream you can hand in FileStream.Handle as the IntPtr (assuming its expecting a HANDLE value)

See "How to pass parameters of Type HANDLE from C# to C++ DLL".

This is heavily dependent on exactly what the SetLogFile method is expecting to receive for the IntPtr parameter. If its expecting a COM object and the C# method implements the appropriate interface you can use the following to pass the variable.

var ptr = Marshal.GetIUnknownForObject(theParameter);
try {
  theComObject.SetLogFile(ptr);
} finally {
  Marshal.Release(ptr);
}

If it's expecting an actual Win32 handle. You'll need to go through the file system API to obtain the handle to the file and then pass it into the method.

You could probably use the SafeFileHandle property of a FileStream object. I'm not sure about the ramifications of doing that, though, so it might be safer to P/Invoke CreateFile.