C++ conversion from to non-scalar type requested

Question

I am trying to overload the + operator as a member function so that I can add two polynomial objects (which are linked lists) together and I keep getting an error message conversion from 'Polynomial*' to non-scalar type 'std::shared_ptr<Polynomial>' requested I don't understand what is causing this? I have declared two shared pointers for my Term objects so I don't understand why I can't do this for a polynomial object?

Polynomial Polynomial::operator+( const Polynomial &other ) const
{
    shared_ptr<Polynomial> result = new Polynomial();
    shared_ptr<Polynomial::Term> a = this->head;
    shared_ptr<Polynomial::Term> b = other.head;
    double sum = 0;

    for(a; a != nullptr; a = a->next)
    {
        for(b; b != nullptr; b = b->next)
        {
            if(a->exponent == b->exponent)
            {
                sum = a->coeff + b->coeff;
                result->head = shared_ptr<Term>(new Term( sum, a->exponent, result->head ));
                cout << "function has found like terms" << endl;
            }
            else if(a->exponent != b->exponent)
            {
                result->head = shared_ptr<Term>(new Term( a->coeff, a->exponent, result->head ));
                cout << "function is working" << endl;

            }
        }
  }
  result;
}

main.cpp

void makePolynomials( shared_ptr [], int &x );

int main()
   {
   shared_ptr<Polynomial> poly[ 100 ];
   int nPolynomials = 0;

   makePolynomials( poly, nPolynomials );
   makePolynomials( poly, nPolynomials );

   for (int j=0; j < nPolynomials; j++)
      cout << *(poly[j]);


    //shows that the addition operator works
    Polynomial c;
    c = *(poly[0])+*(poly[1]);
    cout << c << endl;
}


void makePolynomials( shared_ptr<Polynomial> poly[], int &nPolynomials )
   {
   char filename[20];
   cout << "Enter the filename: ";
   cin >> filename;

   ifstream infile;
   infile.open( filename );
   if (! infile.is_open()) {
      cerr << "ERROR: could not open file " << filename << endl;
      exit(1);
      }

   string polynom;
   while (getline( infile, polynom ))
      {
      poly[ nPolynomials ] = shared_ptr<Polynomial>(new Polynomial( polynom ));
      nPolynomials++;
      }
   }

Answer 1

Here you're requesting an implicit conversion from Polynomial* to std::shared_ptr:

shared_ptr<Polynomial> result = new Polynomial();

But since the std::shared_ptr constructor is explicit, the conversion isn't possible.

You need to pass the Polynomial* explicitly to the std::shared_ptr constructor:

std::shared_ptr<Polynomial> result(new Polynomial);

or using the equivalent new uniform initialization syntax:

std::shared_ptr<Polynomial> result{new Polynomial};