unresolved external symbol visual studio 2010 error

Question

i've implemented with visual studio 2010 professional a solution containing 2 projects; the first called OptDll consist of a dynamic library with a method i want to export, while the second is a exe project, called prova, in order to try the dll. I've included the correct references and all work fine until i decided to insert in OptDll project a new class (GlobalOutput) in order to create the output parameters i want. When i build the project OptDll no error occurs but when i build the whole solution i get these errors in the prova project:

Error   59  error LNK2019: unresolved external symbol "public: __thiscall GlobalOutput::~GlobalOutput(void)" (??1GlobalOutput@@QAE@XZ) referenced in function _main C:\Users\ANTONIO\Desktop\optDll\prova\prova.obj

Error   60  error LNK2019: unresolved external symbol "public: __thiscall GlobalOutput::GlobalOutput(void)" (??0GlobalOutput@@QAE@XZ) referenced in function _main  C:\Users\ANTONIO\Desktop\optDll\prova\prova.obj

Error   61  error LNK1120: 2 unresolved externals   C:\Users\ANTONIO\Desktop\optDll\Debug\prova.exe 1

I read it could be a problem with the class constructor/destructor but i don't fix it. Below the code of interest.

OptFunDll.h
#ifdef OPTFUNDLL_EXPORTS
#define OPTFUNDLL_API __declspec(dllexport) 
#else
#define OPTFUNDLL_API __declspec(dllimport) 
#endif

//#include "tool_library.h"
#include "GlobalOutput.h"

namespace optFun
{
    // This class is exported from the optFunDll.dll
    class myoptFun
    {
    public: 
        // funzione che implementa il modulo di ottimizzazione
        class OPTFUNDLL_API GlobalOutput;
        static OPTFUNDLL_API void scheduling(const char*,const char*,const char*,const char*,GlobalOutput&); 


    };
}

OptFunDll.cpp
#include "stdafx.h"
#include "optFunDll.h"
#include <stdexcept>

using namespace std;

::Random Particle::_rnd;
::Random ParticleSwarm::_rnd;

namespace optFun
{
    void myoptFun::scheduling(const char *pRicette,const char *pWarehouse,const char *pFarmacia,const char *pShaker,GlobalOutput& total){
//here some code...
//class definition
total.CreateDataPrescription(final_list);
total.time=time_output;

GlobalOutput.h
#include <afxwin.h>         // MFC core and standard components
#include <afxext.h>         // MFC extensions
#include <afxadv.h>
#include <afxdisp.h>        // MFC Automation classes
#include <afxdtctl.h>        // MFC support for Internet Explorer 4 Common Controls
#ifndef _AFX_NO_AFXCMN_SUPPORT
#include <afxcmn.h>            // MFC support for Windows Common Controls
#endif // _AFX_NO_AFXCMN_SUPPORT
#include "GlobalInfo.h"
#include "tool_library.h"

struct DataPrescription{
    EDrug  NameDrug;
    double Dosage;
    EContainerType DestType;
    ELiquid IdDest;
    double CapacityDest;
    double Priority;
    bool ScaricoShaker;

    DataPrescription(){
        NameDrug=EDrug_NoDrug;
        Dosage=0.0;
        DestType= EContainerType_Tot;
        IdDest=ELiquid_NoLiquid;
        CapacityDest=0.0;
        Priority=0.0;
        ScaricoShaker=true;
    }

    DataPrescription(EDrug name,double dos,EContainerType dest,ELiquid ID,double cap_dest,double p,bool _ScaricoShaker){
        NameDrug=name;
        Dosage=dos;
        DestType=dest;
        IdDest=ID;
        CapacityDest=cap_dest;
        Priority=p;
        ScaricoShaker=_ScaricoShaker;
    }
};

class GlobalOutput{
public:
    CArray<DataPrescription> OptList;
    time_info time;

    GlobalOutput();
    ~GlobalOutput();

    void CreateDataPrescription(vector<ricetta>&);
};


#endif

GlobalOutput.cpp
#include "stdafx.h"
#include "GlobalOutput.h"

GlobalOutput::GlobalOutput(){
    time.total_makespan=0;
}

GlobalOutput::~GlobalOutput(){
}

void GlobalOutput::CreateDataPrescription(vector<ricetta>& list){

    //DataPrescription tmp;

    for(unsigned int i=0;i<list.size();i++){
        DataPrescription tmp(list[i].getID(),list[i].getdosage(),list[i].get_destination(),list[i].get_DestType(),list[i].get_CapacityDest(),list[i].getPriority(),list[i].processing_info.scarico_shaker);
        this->OptList.Add(tmp);
    }
}

and Finally the main of prova project:

#include "stdafx.h"
#include "optFunDll.h"
#include <iostream>
//#include "C:\Users\ANTONIO\Desktop\optDll\optDll\tool_library.h"

using namespace std;


int main()
{
    const char *pRicette;
    pRicette=new char(NULL);
    const char *pWarehouse;
    pWarehouse=new char(NULL);
    const char *pFarmacia;
    pFarmacia=new char(NULL);
    const char *pShaker;
    pShaker=new char(NULL);
    optFun::myoptFun::GlobalOutput  total;
    optFun::myoptFun::scheduling(pRicette,pWarehouse,pFarmacia,pShaker,total);

    return 0;
}

Thanks for your help. Please let me know if you want more info.

if I comment the code lines under class definition in OptDll.cpp i get these errors: Error 5 error C2079: 'total' uses undefined class 'optFun::myoptFun::GlobalOutput' c:\users\antonio\desktop\optdll\prova\prova.cpp 23

Error   6   error C2664: 'optFun::myoptFun::scheduling' : cannot convert parameter 5 from 'int' to 'optFun::myoptFun::GlobalOutput &'   c:\users\antonio\desktop\optdll\prova\prova.cpp 24

instead if i uncomment the definition of total i obtain also: 9 IntelliSense: incomplete type is not allowed c:\users\antonio\desktop\optdll\optdll\optfundll.cpp 131

Thanks for you availability, I'm new on c++ programming.

Answer 1

You are not actually exporting your class GlobalOutput.

You need to have:

class OPTFUNDLL_API GlobalOutput