What Happened to the CDK?
As of Visual C++ 4.0, the Microsoft OLE Control Development Kit (CDK) became fully integrated with the Microsoft Foundation Class Library (MFC). For 32-bit ActiveX control development, this is the way to go. For 16-bit ActiveX controls, you must still use a 16-bit version of both Visual C++ and the CDK. For more information, see:
ActiveX Controls: Converting a CDK Project to a Visual C++ Project.
ActiveX Controls: Adding an ActiveX Control to an Existing CDK Project.
The first version of the CDK shipped with Visual C++ 2.0. Both 16-bit and 32-bit versions of the CDK were included.
Version 2.1 of Visual C++ included version 1.1 of the CDK, both 16-bit and 32-bit.