DLL Function / Load Library Problem

I'm having a bit of a problem calling a function in a DLL I created. Now it works fine when I call a function which returns void and has no arguments, but when I try to call this function (the following is from the DLL):

Code:

extern "C" _declspec (dllexport) int AddNums (int a, int b)
{
        return (a + b);
}

I get this runtime error:

Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call. This is usually the result of calling a function delcared with one calling convention with a function pointer declared witha a different calling convention.

I can understand what's it's saying, but at the same time I can't because the function pointer... well, see for yourself. Here's the program trying to call the function:

Code:

#include "stdafx.h"

typedef void (WINAPI* DLL_NumberList) ();
typedef int  (WINAPI* DLL_AddNums) (int, int);

DLL_NumberList  NumberList;
DLL_AddNums     AddNums;


int main(int argc, char **argv[])
{
        HINSTANCE       hLib = LoadLibrary ("DLLProj.dll");
        char            cModName[_MAX_PATH];
        int             iAns = 0;

        if (hLib == NULL)
        {
                std::cerr << "Unable to load library!" << std::endl;
                getchar ();
                return 1;
        }
        
        memset (cModName, '\0', _MAX_PATH);
        GetModuleFileName ((HMODULE) hLib, (LPSTR) cModName, _MAX_PATH);
        std::cout << "Library Loaded: " << cModName << std::endl;

        NumberList = (DLL_NumberList) GetProcAddress ((HMODULE) hLib, "NumberList");
        AddNums = (DLL_AddNums) GetProcAddress ((HMODULE) hLib, "AddNums");

        if (NumberList == NULL)
        {
                std::cerr << "Unable to load function NumberList!" << std::endl;
                FreeLibrary ((HMODULE) hLib);
                getchar ();
                return 1;
        }

        if (AddNums == NULL)
        {
                std::cerr << "Unable to load function AddNums!" << std::endl;
                FreeLibrary ((HMODULE) hLib);
                getchar ();
                return 1;
        }

        NumberList ();
        iAns = AddNums (10, 10);
        std::cout << "Answer: " << iAns << std::endl;

        FreeLibrary ((HMODULE) hLib);
	return 0;
}

Now NumberList is loaded / called fine, I just get that runtime error when I try to call AddNums ("iAns = AddNums (10,10);").

UPDATE: Ah strange: When I get the error dialog, if I press Ignore the answer still appears (correctly) in the console (Answer: 20), but the same ESP error persists.

Try to declare function with standard calling convention, like
extern "C" _declspec (dllexport) WINAPI int AddNums (int a, int b)

Hmm I got the following error:

error C2144: syntax error : 'int' should be preceded by ';'

When I added the WINAPI; here it is now:

Code:

extern "C" _declspec (dllexport) WINAPI int AddNums (int a, int b)
{
        return (a + b);
}

Ah I forgot to include windows.h in the dll project, but now I get some warnings:

c:\Documents and Settings\lee\Desktop\DLLProj\DLLProj.cpp(14) : warning C4518: 'int ' : storage-class or type specifier(s) unexpected here; ignored
c:\Documents and Settings\lee\Desktop\DLLProj\DLLProj.cpp(14) : warning C4230: anachronism used : modifiers/qualifiers interspersed; qualifier ignored

Should they present a problem?

UPDATE: Yes, yes they ........ing do. Now it can't load the function. Here's the updated code:

Code:

// DLLProj.cpp
extern "C" _declspec (dllexport) int WINAPI AddNums (int a, int b)
{
        return (a + b);
}

// Program trying to load function
#include "stdafx.h"

typedef void (WINAPI *DLL_NumberList) ();
typedef int  (WINAPI *DLL_AddNums) (int, int);

DLL_NumberList  NumberList;
DLL_AddNums     AddNums;


int main(int argc, char **argv[])
{
        HINSTANCE       hLib = LoadLibrary ("DLLProj.dll");
        char            cModName[_MAX_PATH];
        int             iAns = 0;

        if (hLib == NULL)
        {
                std::cerr << "Unable to load library!" << std::endl;
                getchar ();
                return 1;
        }
        
        memset (cModName, '\0', _MAX_PATH);
        GetModuleFileName ((HMODULE) hLib, (LPSTR) cModName, _MAX_PATH);
        std::cout << "Library Loaded: " << cModName << std::endl;

        NumberList = (DLL_NumberList) GetProcAddress ((HMODULE) hLib, "NumberList");
        AddNums = (DLL_AddNums) GetProcAddress ((HMODULE) hLib, "AddNums");

        if (NumberList == NULL)
        {
                std::cerr << "Unable to load function NumberList!" << std::endl;
                FreeLibrary ((HMODULE) hLib);
                getchar ();
                return 1;
        }

        if (AddNums == NULL)
        {
                std::cerr << "Unable to load function AddNums!" << std::endl;
                FreeLibrary ((HMODULE) hLib);
                getchar ();
                return 1;
        }

        NumberList ();
        iAns = AddNums (10, 10);
        std::cout << "Answer: " << iAns << std::endl;

        FreeLibrary ((HMODULE) hLib);
	return 0;
}

This is starting to really annoy me now. Each time I change something it either makes no difference or the function can't be loaded.

Solved it. Removed WINAPI from the function pointer declaration and it all works fine (I also removed WINAPI from the DLL function declaration).

Change:

Code:

extern "C" _declspec (dllexport) int WINAPI AddNums (int a, int b)
{
        return (a + b);
}

to:

Code:

// DLLProj.cpp
extern "C" _declspec (dllexport)int AddNums (int a, int b)
{
        return (a+b);
}

Get rid of the WINAPI