I am trying to create a function that adds two polynomial coefficients together, basically i have a class polynomial10 and i am creating a function add to add these coefficients together to create a new instance of the class polynomial 10.
Unfortunately when I try to declare the function there comes an error.
Follows the code:

polynomial10 polynomial10::adiciona (polynomial10& p) {
int t = size(coef);
int t2= size(p.coef);
if (t>t2) {
    vector<double> coef_r(t,0);
    for (int i = 0; i < t; i++) {
        if (i<=t2) {
            coef_r[i] += coef[i]+p.coef[i];
    }
    else {
        coef_r[i] += coef[i];
    }
}}
else {
    vector<double> coef_r(t2,0);
    for (int i = 0; i < t2; i++) {
        if (i<=t) {
            coef_r[i] += coef[i]+p.coef[i];
        }
        else {
            coef_r[i] += p.coef[i];
        }
    }
}
polynomial10 p3(coef_r);
return p3;

}

class polynomial10 {
    public:
        vector <double> coef;
        polynomial10( vector <double>& c );
        double evaluate(double x);
        polynomial10 adiciona(polynomial10 p);
};

The function evaluates evaluate the value of the polynomial for a given x and is working properly as previously tested.
I get the following message from VSCode “declaration is incompatible with “polynomial10 polynomial10::adiciona(polynomial10 p)”