passing pointer to dll class function - c++

Question

I need to build an executable which loads the dll # runtime and call the c++ function inside the dll with multiple parameters. I have seen plenty of examples which tells me about how to pass a parameter, but in my case it not exactly the same way. I need to pass 3 parameters.
Struct with 3 std::string elements
Struct pointer with std::map and std::string, and the map has std::string as key and structure as value
Struct with std::unordered_map which also has std::string as key and std::string as value, some bool, integer elements.
The dll class is derived from 2 base classes. ex: BaseClassA --> BaseClassB --> DerivedClassA
I have created the factory function and made all the __dllspec(dllexport) correctly but when I try to create DerivedClassA instance I got exceptions
Unhandled exception at 0x759FA6F2 in rte.exe: Microsoft C++ exception: std::length_error at memory location 0x016FF1C4
My Code Snippet (dllhelp.h):
#include <unordered_map>
#include <cinttypes>
typedef uint32_t ID;
typedef ID EVENT_UID;
typedef struct {
EVENT_UID m_unEventID;
uint8_t *m_ptrMemAddr;
size_t m_dataSize;
}stEvent_t;
typedef struct {
uint32_t m_unOffset;
uint32_t m_unArraySize;
std::string m_acTagName;
std::string m_acTagValue;
std::string m_acDataType;
} stTagElem_t;
typedef std::unordered_map<uint8_t, stTagElem_t> tagsList_t;
typedef struct {
EVENT_UID m_unBindedEvent;
uint16_t m_unMemSize;
tagsList_t m_stTagsList;
std::string m_acMapTypeName;
} stElem_t;
typedef std::unordered_map<std::string, stElem_t> ElemList_t;
typedef struct {
std::string m_acAppBlocName;
std::string m_acInstanceName;
std::string m_acDataMapInstanceName;
std::string m_acTypeName;
} stBlock_t;
typedef std::unordered_map<std::string, std::string > instanceTypeList_t;
typedef struct {
bool m_bIsItOutput;
uint8_t m_unIdxToEvtClient;
EVENT_UID m_acBindedEvent;
instanceTypeList_t m_acParamsList;
} stParams_t;
#ifdef EXPORTING_EXTN
#define RTE_EXTN __declspec(dllexport)
#else
#define RTE_EXTN __declspec(dllimport)
#endif
class RTE_EXTN BaseA {
public:
BaseA(){}
virtual ~BaseA(){}
void rxdEvent(stEvent_t pa_stEvent){ onRxdEvent(pa_stEvent);}
protected:
virtual void onRxdEvent(stEvent_t pa_stEvent);
};
class RTE_EXTN BaseB : public BaseA {
public:
BaseB(stParams_t pa_stParams){;}
virtual ~BaseB(){}
void sendOutput(size_t dataSize);
virtual int initialise() {return -1;}
virtual void onRxdEvent(stEvent_t pa_stEvent) {};
stBlock_t m_stBlock;
stElem_t *m_stElem;
protected:
stEvent_t m_stEvent;
stParams_t m_stParams;
};
class RTE_EXTN DerivedClassA : public BaseB {
public:
DerivedClassA(stBlock_t pa_stBlock, stElem_t *pa_stElem, stParams_t pa_stParams) : BaseB(pa_stParams){
m_stElem = pa_stElem;
m_stBlock = pa_stBlock;
}
int initialise(){return 0;}
void onRxdEvent(stEvent_t pa_stEvent);
};
extern "C" {
RTE_EXTN BaseB* CreateDerivedObj(stBlock_t pa_stBlock, stElem_t *pa_stElem, stParams_t pa_stParams);
};
typedef BaseB* (*CreateDrvObjType_t) (stBlock_t pa_stBlock, stElem_t *pa_stElem, stParams_t pa_stParams);
My dllmain.cpp:
#include "dllhelp.h"
BaseA* CreateDerivedObject(stBlock_t pa_stBlock, stElem_t *pa_stElem, stParams_t pa_stParams)
{
return new DerivedClassA(pa_stBlock, pa_stElem, pa_stParams);
}
My main executable:
stBlock_t m_siInfo;
stElem_t *pa_stElem;
stParams_t m_siParams;
//the above structures are initialized and updated with valid data..
HINSTANCE hGetProcIDDLL_derived;
typedef BaseB* (*CreateDrvObjType_t) (stBlock_t pa_stBlock, stElem_t *pa_stElem, stParams_t pa_stParams);
hGetProcIDDLL_derived = LoadLibrary(TEXT("dllhelp.dll"));
CreateDrvObjType_t oExtension = reinterpret_cast<CreateDrvObjType_t>(GetProcAddress(hGetProcIDDLL_derived, "CreateDerivedObj"));
BaseB* paDrvObj = oExtension(m_siInfo,pa_stElem,m_siParams);
When trying debug mode, I am able to see all the structures were filled with valid elements. But while debugging on the dllmain.cpp, I wasn't able to see any valid data on the structures. Some points to null address, and some to invalid data and many say "Error reading character string".
Note: I don't use dllhelp.h file in my main executable. Rather I have declared all the structures in main file itself.