using matlab::en​gine::MATL​ABEngine from MexFunction::operator() to call the "path" matlab function

From the Matlab Command Window, calling for path works normally.

From a C++-mexFunction I try to do the same.

Doing so, I have this error :

void MexFunction::operator()(mm::ArgumentList outputs, mm::ArgumentList inputs)
{
  auto matlabptr = getEngine();
  matlab::data::ArrayFactory f;
  auto emptyArray = f.createScalar("");
  auto path = matlabptr->feval(matlab::engine::convertUTF8StringToUTF16String("path"),emptyArray);
  if (path.getNumberOfElements() > 0) {
	  std::string myPath = matlab::data::TypedArray<matlab::data::MATLABString>(path)[0];
	  std::cout << myPath << std::endl;
  }else{
    std::cout << "Rate" <<std::endl;
  }
}

Where do I goof ?

-----------------------

Edit and solve

path with one argument written this way in the `Command Window` will generate this error. I wanted to call it with no arguments, thus I had to do the following

void MexFunction::operator()(mm::ArgumentList outputs, mm::ArgumentList inputs)
{
  md::TypedArray<md::MATLABString> values = inputs[0];
  std::cout << "Going to run " << (std::string)values[0] <<std::endl;
  auto matlabptr = getEngine();
  matlab::data::ArrayFactory f;
  auto emptyArray = f.createEmptyArray();
  auto res = matlabptr->feval((std::string)values[0],1, {}); // <- this is the correct interface to call
  auto tmp = md::CharArray(res[0]);
  std::cout << tmp.toAscii() << std::endl;
}

Answer 1

[Vincent Huber]

This is the correct call to feval for command with no arguments:

auto res = matlabptr->feval((std::string)values[0],1, {});