How do I port my 16-bit DLL to a Win32 DLL?
If you have built 16-bit DLLs for Windows 3.x, you should find that building 32-bit DLLs is more convenient. Visual C++ offers more direct support, which can save you several steps in DLL creation. For more information, see Differences Between Win16 and Win32 DLLs.
The differences between Win16 and Win32 DLLs require more than just a simple recompilation to turn your Win16 DLL into a Win32 DLL. For more information about porting 16-bit DLLs to Win32 DLLs, see the Knowledge Base article, "How to Port a 16-bit DLL to a Win32 DLL" (Q125688).