Linking with a dll compiles, but causes a segfault

Question

I\'ve been working on compiling with Visual Studio 2015 a large number of code files written originally for use on linux, using g++. Specifically, I need a .dll for use with

Answer 1

The static data in the dll is in a different address space so you can't directly reference it (the call has to be mapped thru an import table). When you link a static library everything is in the address space of the executable so you can.

You must use dllexport and dllimport as a pair. dllexport where you define them in the shared library (dll) and dllimport where you use them in the application. You'll typically have a macro that evaluates to either __declspec(dllexport) or __declspec(dllimport) depending on where it's used. E.g.

#ifdef _DLL     // inside the DLL
  #define DLLExportImport __declspec(dllexport)
#else          // outside the DLL
   #define DLLExportImport __declspec(dllimport)
#endif

And use it where you define the class:

class DLLExportImport FirstClass
{ ... };

Defining the symbol _DLL as appropriate in the respective projects. Visual Studio predefines _DLL when you create a new dll project.

There is no need for .def files in most cases these days.