.dll Matlab Engine
Thanks! Good input. Now I know a little bit more:
I get error:
main.obj : error LNK2019: unresolved external symbol '_engOpen' referenced in function ""bool __stdcall StartVirtualEngineMatlab(void)" (?StartVirtualEngineMatlab@@YG_NXZ)"
Same for "_engClose"
And:
MSVCRTD.lib(crtexe.obj) : error LNK2019: unresolved external symbol '_main' referenced in function "___tmainCRTStartup"
Yes Matlab is correctly installed and since I only have one Matlab version the header-files are also the right ones. It's just a Matlab Engine problem here:
I compiled the Matlab Enngine sample engwindemo.c with the lcc compiler from Matlab. (Following the instructions http://www.mathworks.com/help/techdoc/matlab_external/f39903.html)
Then I tested the .exe-file wiith Dependency Walker that gave me this result:
Error: At least one module has an unresolved import due to a missing export function in an implicitly dependent module. (ADVAPI.DLL, LIBUT.DLL, USER32.DLL)
Warning: At least one module has an unresolved import due to a missing export function in a delay-load dependent module. (MPR.DLL, SHLWAPI.DLL)
If I compile with Visual C++ I get the same message from Dependency Walker. And it's actually the same error with my .dll
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Hi
I have a problem loading a .dll I've written to connect MetaTrader to Matlab. Error is 126 "cannot load library". I've been trying to solve this since a week now and tried quite a lot:
Reference is: https://www.mql5.com/en/articles/1567
I'm using Visual C++ 2010.
For learning reasons I've written a very simple .dll that worked without any problems:
#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include "stdafx.h"
#define MT4_EXPFUNC __declspec(dllexport)
//+------------------------------------------------------------------+
//| |
//+------------------------------------------------------------------+
BOOL APIENTRY DllMain( HMODULE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
break;
}
return TRUE;
}
MT4_EXPFUNC int _stdcall PlusZwei(int zahl1, int zahl2)
{
int res = 0;
res = zahl1+zahl2;
return(res);
}
This code I modified step by step. I also compiled a .def-file within the project. And I added the path to the .lib-files needed for Matlab Engine within Visual C++. The last code working is this:
//Update 2 ->3: delete #define MT4_EXPFUNC __declspec(dllexport)
// add extern "C" __declspec(dllexport) int __stdcall PlusZwei(int zahl1, int zahl2);
// add int _stdcall PlusZwei(int zahl1, int zahl2)
//Update 3 ->4: add #include "engine.h"
// dllmain.cpp : Definiert den Einstiegspunkt für die DLL-Anwendung.
#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "stdafx.h"
#include "engine.h"
extern "C" __declspec(dllexport) int __stdcall PlusZwei(int zahl1, int zahl2);
//extern "C" __declspec(dllexport) bool __stdcall StartVirtualEngineMatlab(void);
//extern "C" __declspec(dllexport) bool __stdcall StoppVirtualEngineMatlab(void);
//#define MT4_EXPFUNC __declspec(dllexport)
#define BUFSIZE 256
Engine *pEng;
mxArray *Summand1 = NULL, *Summand2 = NULL, *mxSumme = NULL;
//int Output;
//#define MT4_EXPFUNC __declspec(dllexport)
//+------------------------------------------------------------------+
//| |
//+------------------------------------------------------------------+
BOOL WINAPI DllMain( HMODULE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
//pEng = NULL;
//StartVirtualEngineMatlab();
break;
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
//StoppVirtualEngineMatlab();
break;
}
return TRUE;
}
/*
bool __stdcall StartVirtualEngineMatlab()
{//Ãîòîâíîñòü: 100%. Ñîçäàíèå âèðò/ìàøèíû
//** Èíèöèàëèçàöèÿ âèðò/ìàøèíû
if ((pEng = engOpen(NULL)) == NULL)
{
MessageBoxA(NULL, (LPSTR)"Can't start MATLAB engine!",
(LPSTR) "MatLab Engine: ERROR!", MB_OK|MB_ICONSTOP);
return FALSE; //Âîçíèêëè ïðîáëåìû çàïóñêà âèðò/ìàøèíû
};
//
return TRUE;
}
//---------------------------------------------------------------------------
bool __stdcall StoppVirtualEngineMatlab()
{//Ãîòîâíîñòü: 100%. Óíè÷òîæåíèå âèðò/ìàøèíû
//** Äåèíèöèàëèçàöèÿ âèðò/ìàøèíû
engClose(pEng);
//
return TRUE;
}
int __stdcall PlusZwei(int zahl1, int zahl2)
{
Summand1 = mxCreateDoubleMatrix(1, 1, mxREAL);
Summand2 = mxCreateDoubleMatrix(1, 1, mxREAL);
mxSumme = mxCreateDoubleMatrix(1, 1, mxREAL);
memcpy((char *)mxGetPr(Summand1), (char *)zahl1, 1);
engPutVariable(pEng, "a", Summand1);
memcpy((char *)mxGetPr(Summand2), (char *)zahl2, 1);
engPutVariable(pEng, "b", Summand2);
engPutVariable(pEng, "Summe", mxSumme);
engEvalString(pEng, "Summe = a + b;");
mxSumme = engGetVariable(pEng, "Summe");
memcpy((char *)Output, (char *)mxGetPr(mxSumme), 1);
//int res = 0;
//res = zahl1+zahl2;
return(1);
}
*/
int _stdcall PlusZwei(int zahl1, int zahl2)
{
int res = 0;
res = zahl1+zahl2;
return(res);
}
The problems begin when I try to start Matlab Engine in the next step as seen in the code above in comments. I don't use Matlab to calculate anything - just start and stop it in BOOL WINAPI DllMain() in the switch. If I do so I get error 126! Also note that in the working code above definition Engine *pEng; does not lead to an error. So I think engine.h must be working somehow???
So how can I solve this? I suppose engine.h is not working correctly? But I included it in the project and compiled it within the project.
Would be very glad if someone has an idea to this matter!
Thanks in advance!
Max