Using calllib with a function that uses std::vector in its prototype

Hi folks,

Is there any way to use loadlibrary/calllib to call a function in a DLL where the function is expecting a std::vector as one of the inputs? Or am I trying to do something impossible?

Here is what I get when I try to run loadlib using a header file that includes address pointers (&) to two std::vector.

Warning: Warnings messages were produced while parsing.  Check the functions you
intend to use for correctness.  Warning text can be viewed using:
 [notfound,warnings]=loadlibrary(...) 
> In loadlibrary 
Error loading library intermediate output follows.
The actual error is at the end of this output.
*********

Failed to parse type 'std :: vector < double >* filterCoeffs' original input 'std :: vector < double >& filterCoeffs '
Found on line 23 of input from line 68 of file C:\\_EMILY\\NASARovers_2328\\NASARovers\\Matlab\\Matlab_Rovers_header2.h
Error parsing argument for function filtfilt_1D function may be invalid.

Failed to parse type 'std :: vector < double >* toFilter' original input ' std :: vector < double >& toFilter '
Found on line 23 of input from line 68 of file C:\\_EMILY\\NASARovers_2328\\NASARovers\\Matlab\\Matlab_Rovers_header2.h
Error parsing argument for function filtfilt_1D function may be invalid.
*********
Error using loadlibrary
Building NASARovers_thunk_pcwin64 failed.  Compiler output is:
C:\TDM-GCC-64\bin\gcc -I"C:\Program Files\MATLAB\R2016a\extern\include"
-fexceptions -fno-omit-frame-pointer -I"C:\MATLAB"
-I"C:\_EMILY\NASARovers_2328\NASARovers\Matlab" "NASARovers_thunk_pcwin64.c" -o
"NASARovers_thunk_pcwin64.dll" -shared
In file included from NASARovers_thunk_pcwin64.c:27:0:
C:\_EMILY\NASARovers_2328\NASARovers\Matlab/Matlab_Rovers_header2.h:68:37:
error: expected ')' before ':' token
 NASAROVERS_CAPI void filtfilt_1D(std::vector<double>& filterCoeffs,
 std::vector<double>& toFilter);
                                     ^
NASARovers_thunk_pcwin64.c:141:29: error: expected '=', ',', ';', 'asm' or
'__attribute__' before ':' token
 EXPORT_EXTERN_C void
 voidstd::vector<double>&filterCoeffsstd::vector<double>&toFilterThunk(void
 fcn(),const char *callstack,int stacksize)

[mezaguer karima]

hello i have seen your question i'm in the same probleme i have this in my program std::vector<unsigned int> vuiInterfaces(MAX_INTERFACE_COUNT) C++ and i don't know how to use it in matlab (MAX_INTERFACE_COUNT= 5 here) this is the part of c++ code, how can i convert this vector into matlab to use it

thanks

#include "stdafx.h"
#include <iostream>
#include <conio.h>
#include "InterfaceLLT_2.h"
#include "PartialProfile.h"

using namespace std;

static CInterfaceLLT* m_pLLT = NULL;
static unsigned int m_uiResolution = 0;
static TScannerType m_tscanCONTROLType = scanCONTROL2xxx;

int main(int argc, char* argv[])
{
	UNREFERENCED_PARAMETER(argc);
	UNREFERENCED_PARAMETER(argv);
	std::vector<unsigned int> vuiInterfaces(MAX_INTERFACE_COUNT);
	std::vector<DWORD> vdwResolutions(MAX_RESOULUTIONS);
	unsigned int uiInterfaceCount = 0;
	unsigned int uiShutterTime = 100;
	unsigned int uiIdleTime = 900;
	TScannerType ScannerType = scanCONTROL2xxx;
	bool bLoadError = false;
	int iRetValue = 0;
	bool bOK = true;
	bool bConnected = false;

	// Creating a LLT-object
	// The LLT-Object will load the LLT.dll automaticly and give us a error if ther no LLT.dll
	m_pLLT = new CInterfaceLLT("..\\LLT.dll", &bLoadError);

	if (bLoadError)
	{
		cout << "Error loading LLT.dll \n";

		// Wait for a keyboard hit
		while (!_kbhit()) {}

		// Deletes the LLT-object
		delete m_pLLT;
		return -1;
	}

	// Create a Device
	if (m_pLLT->CreateLLTDevice(INTF_TYPE_ETHERNET))
		cout << "CreateLLTDevice OK \n";
	else
		cout << "Error during CreateLLTDevice\n";

	// Gets the available interfaces from the scanCONTROL-device
	iRetValue = m_pLLT->GetDeviceInterfacesFast(&vuiInterfaces[0], (unsigned int)vuiInterfaces.size());

	if (iRetValue == ERROR_GETDEVINTERFACES_REQUEST_COUNT)
	{
		cout << "There are more or equal than " << vuiInterfaces.size() << " scanCONTROL connected \n";
		uiInterfaceCount = (unsigned int)vuiInterfaces.size();
	}
	else if (iRetValue < 0)
	{
		cout << "A error occured during searching for connected scanCONTROL \n";
		uiInterfaceCount = 0;
	}
	else
	{
		uiInterfaceCount = iRetValue;
	}

Answer 1

[Philip Borghesani]

What you are trying won't work.

loadlibrary only supports calling functions that are callable from C and header files that can be parsed by a c compiler. Any functions written in C++ must be extern "C" and std:vector or any class or template type can't be used for input or output arguments.

I will suggest the documentation make this a bit more explicit.

[Dan K]

I was afraid that was going to be the answer, but was hoping I was wrong. Many thanks.

Answer 2

[Todd Leonhardt]

As mentioned, you can't really use calllib with most C++ code.

However, you can use mex to build a MATLAB Executable (MEX) function from C++ source code: http://www.mathworks.com/help/matlab/ref/mex.html

MEX is relatively flexible in that it will let you also link to C++ static and dynamic libraries as well as compile source code. It is a little bit more work in that you need to create a wrapper mexFunction and deal with marshaling data between MATLAB and C/C++, but it is MUCH more flexible than calllib.

Answer 3

[Dan K]

In case anybody has stumbled across this question, I will tell you what my final solution ended up being. For each top level function that uses std::vectors as inputs or outputs, I wrote a wrapper function that surrounds it, taking standard data pointers and the size of the intended vector and constructs the vectors before calling the actual function I wanted to test. Then repeat the process once the function has returned.

Example:

void InterpolateDelayEst_MLTest(
  double* delayEstRawPtr, double* delayEstPtr, UINT32 nRaw, FLOAT32 delayEstBW, UINT32 interp_scalar_m_length)
  {
  // Create the vectors that the data is going to be dropped into:
  std::vector<FLOAT32> delayEstRaw(nRaw);
  std::vector<FLOAT32> delayEst(interp_scalar_m_length);
  for (UINT32 i = 0; i < nRaw; i++)
    delayEstRaw[i] = (FLOAT32)delayEstRawPtr[i];
// Call the actual function that we are interested in testing:
    InterpolateDelayEst(delayEstRaw, delayEst, delayEstBW,  interp_scalar_m_length);
// Copy the data from the returned vector into the array whose pointer was passed in.
    for (UINT32 i = 0; i < interp_scalar_m_length; i++)
    delayEstPtr[i] = (double)delayEst[i];
  }