What does classname functionname(const classname & objectname) means?

Question

I have an assigment where we should do resistor calculations (series and parallel) using the following class :

class R1 {

protected:
   double R , cost_in_euro ;
      string unit ;
public :

   R1(double R , const string & unit , double cost_in_euro);
   R1(double R , double cost_in_euro);
   R1(double R);
   R1(const R1 & R);


   R1 serie(const R1 & R1);
   R1 parallel(const R1 & R1);



};

My question is regarding the functions serie and parallel . How am i supposed to add 2 resistors using a function that only takes one single object as an argument?

Answer 1

You only need one parameter because the class contains the information for one R, and the parameter contains the information for the other R.

    class R1 {
        protected:
        double R , cost_in_euro ;
            string unit ;
        public :

        R1(double R , const string & unit , double cost_in_euro);
        R1(double R , double cost_in_euro);
        R1(double R);
        R1(const R1 & R);


        R1 serie(const R1 & other)
        {
            double total = other.R + R;
            return R1(total);
        }

        R1 parallel(const R1 & other)
        {
            double r1 = other.R;
            double r2 = R;
            double total = (r1*r2)/(r1 + r2);

            return R1(total);
        }

    };