Abstract property

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Abstactprogram
{
    public abstract class Program
    {
        public Program()
{
}
private int age = 0;
// Normal property
public int Age_Normal
{
get
{
return age;
}
set
{
age = value;
}
}
// Abstract property
public abstract string Address_Abstract
{
get;
set;
}
// Normal Methods
public string GetName(string firstName, string lastName)
{
return "My Name is : " + GetName_Virtual(firstName, lastName);
}
public int Divide_NotAbstract(int a, int b)
{
return a / b;
}
// Abstract Methods
public abstract int Add_Abstract(int a, int b);
public abstract int Subtract_Abstract(int a, int b);
 
// Virtual method
public virtual string GetName_Virtual(string firstName, string lastName)
{
return firstName + " " + lastName;
}
    }
    public class DerivedClass : Program
    {
        private string address = string.Empty;
        public DerivedClass()
        {
        }
        // override the abstract property
        public override string Address_Abstract
        {
            get
            {
                return address;
            }
            set
            {
                address = value;
            }
        }
        // override the abstract method
        public override int Add_Abstract(int a, int b)
        {
            return a + b;
        }
        public override int Subtract_Abstract(int a, int b)
        {
            return a - b;
        }
        // override virtual method
        public override string GetName_Virtual(string firstName, string lastName)
        {
            return "(Overriden) Name: " + firstName + " " + lastName;
        }
        // hide normal method of the abstract class
        public new string Divide_NotAbstract(int a, int b)
        {
            int d = a / b;
            return "The division is: " + d.ToString();
        }
        // use abstract property to retrieve its value
        public string GetAddress()
        {
            return Address_Abstract;
        }


        static void Main(string[] args)
        {
            DerivedClass c = new DerivedClass();
           Console.Write("<b>Abstract method - Sum: </b>" + c.Add_Abstract(50, 30).ToString() + "<br />");
           Console.Write("<b>Abstract method - Subtract: </b>" + c.Subtract_Abstract(50, 30).ToString() + "<br />");
           Console.Write("<b>Virtual Method - GetName_Virtual: </b>" + c.GetName_Virtual("SHEO", "NARAYAN") + "<br />");
           Console.Write("<b>Normal Public Method - GetName: </b>" + c.GetName("SHEO", "NARAYAN") + "<br />");
           Console.Write("<b>Normal Public Method being hidden using new keyword - Divide_NotAbstract: </b>" + c.Divide_NotAbstract(50, 30).ToString() + "<br />");
            Program p = new DerivedClass();
            Console.Write("<b>Normal Public Method from Abstract Class - Divide_NotAbstract: </b>" + p.Divide_NotAbstract(50, 30).ToString() + "<br />");
            c.Address_Abstract = "Sheo Narayan, Hitec City, Hyderabad.";
            Console.Write("<b>Normal Public method accessing <br />overriden Abstract Property - GetAddress: </b>" + c.GetAddress() + "<br />");
            Console.ReadLine();
        }
    }
}