CODEWITHSUNDEEP
c++
user3558533
user3558533

Reputation: 13

Operator overloading problems C++

I have a Polynomial class and I have overloaded the +,-, and * operators, as well as the << operator. It all seems to work fine until I try to output an expression such as poly1+poly2 rather than just a single Polynomial object.

Here is my addition operator code:

Polynomial operator+ (const Polynomial& poly1, const Polynomial& poly2){
    vector<int> final_coeffs;

    if (poly1.Degree()>poly2.Degree())
    {
        for (int i=0; i<=poly2.Degree(); i++)
            final_coeffs.push_back(poly2.Coefficient(i) + poly1.Coefficient(i));
        for (int i=poly2.Degree()+1; i<=poly1.Degree(); i++)
            final_coeffs.push_back(poly1.Coefficient(i));
    }

    else
    {
        for (int i=0; i<=poly1.Degree(); i++)
            final_coeffs.push_back(poly1.Coefficient(i) + poly2.Coefficient(i));
        for (int i=poly1.Degree()+1; i<=poly2.Degree(); i++)
            final_coeffs.push_back(poly2.Coefficient(i));
    }

    return Polynomial(final_coeffs);
}

And here is my << operator code (I already have a correctly working print member function):

ostream& operator<< (ostream& out, Polynomial& poly){
    poly.print();
    return out;
}

The problem arises when I try to do this in main:

cout << poly1+poly2;

But works fine if I just do:

cout << poly1;

The error message says: Invalid operands to binary expression ('ofstream' (aka 'basic_ofstream') and ('Polynomial')

And for the specific function it should be using: Candidate function not viable: expects an l-value for 2nd argument

Thank you!

Upvotes: 1

Views: 1863

Answers (1)

M.M
M.M

Reputation: 141598

You need:

ostream& operator<< (ostream& out, Polynomial const& poly) {

This is because a temporary object cannot be bound to a non-const reference.

Note that this means you also must make the Polynomial::print() function be const.

Upvotes: 4

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