What is the difference between dllexport and dllimport?
Solution 1:
__declspec( dllexport )
- The class or function so tagged will be exported from the DLL it is built in. If you're building a DLL and you want an API, you'll need to use this or a separate .DEF file that defines the exports (MSDN). This is handy because it keeps the definition in one place, but the .DEF file provides more options.
__declspec( dllimport )
- The class or function so tagged will be imported from a DLL. This is not actually required - you need an import library anyway to make the linker happy. But when properly marked with dllimport
, the compiler and linker have enough information to optimize the call; without it, you get normal static linking to a stub function in the import library, which adds unnecessary indirection. ONT1 ONT2
Solution 2:
__declspec(dllexport)
tells the linker that you want this object to be made available for other DLL's to import. It is used when creating a DLL that others can link to.__declspec(dllimport)
imports the implementation from a DLL so your application can use it.
I'm only a novice C/C++ developer, so perhaps someone's got a better explanation than I.