Understanding Up Casting and Down Casting (C# reference)

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace Apps

{

    class Doctor1

    {

        protected string name, specialization;

        public Doctor1(string name, string specialization)

        {

            this.name = name;

            this.specialization = specialization;

        }

        public void Print()

        {

            Console.WriteLine(name);

            Console.WriteLine(specialization);

        }

    }

    class ResidentalDoctors1 : Doctor1

    {

        protected int salary;

        public ResidentalDoctors1(string name, string specialization, int salary)

            : base(name, specialization)

        {

            this.salary = salary;

        }

        public new void Print()

        {

            base.Print();

            Console.WriteLine(salary);

        }

        public int GetPay()

        {

            return salary;

        }

    }

    class Consultant1 : Doctor1

    {

        protected int fees, visitNum;

        public Consultant1(string name, string specialization, int fees, int visitNum)

            : base(name, specialization)

        {

            this.fees = fees;

            this.visitNum = visitNum;

        }

        public new void Print()

        {

            base.Print();

            Console.WriteLine(fees);

            Console.WriteLine(visitNum);

        }

        public int GetPay()

        {

            return fees * visitNum;

        }

    }

    class UnderstandingUpDownCasting

    {

        public static void Main()

        {

            //ResidentalDoctors rd = new ResidentalDoctors("Steve", "General", 100);

            //Consultant c = new Consultant("Chitti", "General", 300, 10);

            Doctor1 d = new Consultant1("Chitti", "General", 300, 10);  // Upcasting

            Consultant1 c;

            c = (Consultant1)d; //Downcasting

            //Console.WriteLine(d.GetPay());

            //Console.WriteLine(c.GetPay());

            //rd.Print();

           // c.Print();

        }

    }

}