COM Interoperability

COM Interoperability

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 Marshaling

Com Data Type	.NET  Framework Type
bool Int32	char, small SByte
Short	Int16l
unsigned char, byte	Byte
wchar_t, unsigned short	UInt16
unsigned long, unsigned int	UINT32
unsigned hyper	UInt64
float	single
double	Double
VARIANT BOOL	Boolean
void *	IntPtr
HRESULT	Int16 or IntPtr
CURRENCY	decimal
SCODE	Int32
LPSTR	String
LPWSTR	Object
VARIANT	Object
DECIMAL	Decimal
IDispatch	object
DATE	Date Tiime
BSTR	String
IUnknown*	Object
SAFEARRAY(type)	type[]
long,	int Int32