Using the COM Interop functions provided by the .NET Framework, you can gain access to all the objects, methods, and events that are exposed by any COM object simply by establishing a reference to it. This includes previous versions of ADO and COM objects that you’ve developed using them. The .NET Framework creates an interop assembly that handles communication between The .NET Framework and COM.The interop assembly handles a number of tasks, but the most important is data type marshaling.
|Com Data Type||.NET Framework Type|
|bool Int32||char, small SByte|
|unsigned char, byte||Byte|
|wchar_t, unsigned short||UInt16|
|unsigned long, unsigned int||UINT32|
|HRESULT||Int16 or IntPtr|
|DATE Date Tiime||Date Tiime|