topic Re: Error LNK2019 when using dll maker in FlexSim Forum

Error LNK2019 when using dll maker

yexioamu — Fri, 28 Jul 2023 09:47:14 GMT

[ FlexSim 21.2.4 ]

When i implement some function which build in dll release mode, occur a error liked this :

error LNK2019: Unresolved external symbol "__declspec(dllimport) public: __cdecl FlexSim::Map::~Map(void)" (__imp_??1Map@FlexSim@@QEAA@XZ)

what should i do fo it?

Re: Error LNK2019 when using dll maker

kavika_faleumu — Fri, 28 Jul 2023 17:05:44 GMT

Microsoft's documentation states that "LNK2019 can occur when a declaration exists in a header file, but no matching definition is implemented. For member functions or static data members, the implementation must include the class scope selector." So, it looks like there's a FlexSim::Map::~Map(void) defined in the header somewhere, but no implementation?

Could you provide more information like what you're implementing and where you're implementing it? Thank you.

Re: Error LNK2019 when using dll maker

JordanLJohnson — Fri, 28 Jul 2023 17:48:45 GMT

The DLL Maker can only access a limited set of types and functions. The Variant class and Map class are not accessible from the DLL Maker.

If you use the Module SDK, you can access both those classes, as well as many others.

Re: Error LNK2019 when using dll maker

yexioamu — Fri, 28 Jul 2023 23:00:24 GMT

When I built it in debug model，it did’t occur the error

Re: Error LNK2019 when using dll maker

kavika_faleumu — Mon, 31 Jul 2023 17:06:01 GMT

@yexioamu

Re: Error LNK2019 when using dll maker

kavika_faleumu — Tue, 01 Aug 2023 15:08:38 GMT

@yexioamu, can you share with us what you're trying to do? Maybe that will help us try to replicate your error. Thank you.

Re: Error LNK2019 when using dll maker

yexioamu — Tue, 01 Aug 2023 15:13:27 GMT

Sorry, I will show you tomorrow, I am on a business trip.

Re: Error LNK2019 when using dll maker

yexioamu — Wed, 02 Aug 2023 02:27:01 GMT

My function is simple, this is one of my function in mydll.cpp, it is a simple UUID function:

// C LIBRARY FOR INPUT/OUTPUT STREAMS
#include <stdio.h>
// IN ORDER TO HAVE ACCESS TO FLEXSIM FUNCTIONS, INCLUDE FLEXSIMDEFS.H
#include "FlexsimDefs.h"

#include <iostream>
#include <windows.h>
#include <winhttp.h>
#include <websocket.h>
#include <vector>
#include <time.h>
#include <sys/timeb.h>
#include <string>
#include <atlstr.h>
#include <thread>

#pragma comment(lib, "Websocket.lib")
#pragma comment(lib, "winhttp.lib")
using namespace std;

//#define CHROME_USER_AGENT TEXT("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.54 Safari/537.36")
#define CHROME_USER_AGENT TEXT("Apache-HttpClient/4.5.12 (Java/11.0.6)")


__declspec(dllexport) Variant UUIDF(FLEXSIMINTERFACE)
{
//struct timeb stb;
//::ftime(&stb);
//::srand((unsigned)stb.millitm);

LARGE_INTEGER nStartCounter;
::QueryPerformanceCounter(&nStartCounter);
::srand((unsigned)nStartCounter.LowPart);


//srand((unsigned)time(NULL));
CString strRand;
long long time_last = time(NULL);
struct timeb t1;
ftime(&t1);
long long t2 = t1.time * 100000 + t1.millitm * 100 + rand();
int letter1 = 'A' + rand() % 26;
int letter2 = 'A' + rand() % 26;
int letter3 = 'A' + rand() % 26;

string t3 = to_string(t1.time) + (char)letter1 + (char)letter2 + to_string(t1.millitm) + (char)letter3;

return t3

when i build it in debug model, it builds success, but in release model, it occur the error:

error LNK2019: Unresolved external symbol "__declspec(dllimport) public: __cdecl FlexSim::Map::~Map(void)" (__imp_??1Map@FlexSim@@QEAA@XZ)

and in my other mydll function, it occur in release model too.

Re: Error LNK2019 when using dll maker

kavika_faleumu — Wed, 02 Aug 2023 16:31:33 GMT

After copying your code into a DLL Maker and updating the Solution Properties (i.e., updating the C/C++ Language Standards to use ISO C17 and C++17 and updating the Platform Toolset to use Visual Studio 2019 (v142)), I don't get the LNK2019 error you're getting. Are you sure this is the function throwing the error? I don't see a Map being used in this code, which is what looks to be causing this error somehow.

Re: Error LNK2019 when using dll maker

yexioamu — Thu, 03 Aug 2023 00:45:14 GMT

I use the same C/C++ Language Standards and Platform Toolset as you. In my UUIDF function, i did't used a Map, but it still occur this error, and in my other function which without Map, this LNK2019 error occur too in release model.

Re: Error LNK2019 when using dll maker

kavika_faleumu — Sat, 05 Aug 2023 19:59:01 GMT

@yexioamu, I'm confused as to why you're getting this error and I'm not since we're using the same settings. Would you mind uploading the files you're using? I would like to take a look at them.

If they contain sensitive information, you could make the question private so only certain FlexSim Employees can see them.

Re: Error LNK2019 when using dll maker

julie_weller — Wed, 09 Aug 2023 21:10:33 GMT

Hi @yexioamu, was Jordan Johnson's answer helpful? If so, please click the "Accept" button at the bottom of their answer. Or if you still have questions, add a comment and we'll continue the conversation.

If we haven't heard back from you within 3 business days we'll auto-accept an answer, but you can always comment back to reopen your question.