|Important||This document may not represent best practices for current development, links to downloads and other resources may no longer be valid. Current recommended version can be found here.|
The dllexport and dllimport storage-class attributes are Microsoft-specific extensions to the C and C++ languages. They enable you to export and import functions, data, and objects to and from a DLL.
These attributes explicitly define the DLL's interface to its client, which can be the executable file or another DLL. Declaring functions as dllexport eliminates the need for a module-definition (.DEF) file, at least with respect to the specification of exported functions. Note that dllexport replaces the __export keyword.
If a class is marked declspec(dllexport), any specializations of class templates in the class hierarchy are implicitly marked as declspec(dllexport). This means templates are explicitly instantiated and its members must be defined.
dllexport of a C++ function will expose the function with C++ name mangling. If C++ name mangling is not desired, either use a .def file (EXPORTS keyword) or declare the function as extern "C".
The declaration of dllexport and dllimport must use extended attribute syntax and the __declspec keyword.
// Example of the dllimport and dllexport class attributes __declspec( dllimport ) int i; __declspec( dllexport ) void func();
Alternately, to make your code more readable, you can use macro definitions:
#define DllImport __declspec( dllimport ) #define DllExport __declspec( dllexport ) DllExport void func(); DllExport int i = 10; DllImport int j; DllExport int n;
For additional information, see:
END Microsoft Specific