Export from a DLL Using __declspec(dllexport)

You can export data, functions, classes, or class member functions from a DLL by using the __declspec(dllexport) keyword. If you use __declspec(dllexport), you do not need a .DEF file for exports.

To export functions, the __declspec(dllexport) keyword must appear to the left of the calling-convention keyword, if a keyword is specified. For example:

__declspec(dllexport) void __cdecl Function1(void);

To export all the public data members and member functions in a class, the keyword must appear to the left of the class name as follows:

class __declspec(dllexport) CExampleExport : public CObject
{ ... class definition ... };

When building your DLL, you typically create a header file that contains the function prototypes and/or classes you are exporting, and add the __declspec(dllexport) to the declarations in the header file. To make your code more readable, define a macro for __declspec(dllexport) and then use the macro with each symbol you are exporting:

#define DllExport   __declspec( dllexport )

__declspec(dllexport) stores function names in the DLL’s export table. If you want to optimize the table’s size, see Export Functions From a DLL By Ordinal Rather Than By Name.

Note   When porting DLL source code from Win16 to Win32, replace each instance of __export with __declspec(dllexport).