Create & Using Dll's On MFC Application

Question

I just created dll project in Visual Studio 2013:
New Project->MFC DLL->Next->Check "MFC Extention DLL" and finish.
Now, I add new class:

class CMyTest
 {
  public:
CMyTest();
~CMyTest();

int Test(){ return 1; }

};

Next, I compiled the project and got .lib,.dll files.

In the another project (who using the dll's) I just add the include,lib directory and copy the .dll file to the .exe file location and add the .lib file to Additional Dependency on Linker->Input.
Now, i just create some object from CMyTest class on my OnInitDialog() Method:

CMyTest x;

And when I tried to compiled the project I got Link error:

Error   3   error LNK2019: unresolved external symbol "public: __cdecl CMyTest::CMyTest(void)" (??0CMyTest@@QEAA@XZ) referenced in function "protected: virtual int __cdecl CUsingDllProjectDlg::OnInitDialog(void)" (?OnInitDialog@CUsingDllProjectDlg@@MEAAHXZ)   C:\Users\user\documents\visual studio 2013\Projects\UsingDllProject\UsingDllProject\UsingDllProjectDlg.obj  UsingDllProject
Error   4   error LNK2019: unresolved external symbol "public: __cdecl CMyTest::~CMyTest(void)" (??1CMyTest@@QEAA@XZ) referenced in function "protected: virtual int __cdecl CUsingDllProjectDlg::OnInitDialog(void)" (?OnInitDialog@CUsingDllProjectDlg@@MEAAHXZ)  C:\Users\user\documents\visual studio 2013\Projects\UsingDllProject\UsingDllProject\UsingDllProjectDlg.obj  UsingDllProject

Where is the problem?

Evyatar Elmaliah Evyatar Elmaliah · Accepted Answer · 2015-11-28T18:22:04

You need to declare the Test method like that (and also the ctr,dctr):

__declspec(dllexport) int Test(){ return 1; }

__declspec(dllexport), instruct the linker to export a symbol to a DLL.
you can read about that here: https://msdn.microsoft.com/en-us/library/dabb5z75(VS.80).aspx

Create & Using Dll's On MFC Application

1 Answers