using System;

public delegate void ShippingFeeDelegate(double thePrice, ref double fee);

​

public class Program

{

    public static void Main()

    {

        ShippingFeeDelegate theDel;

        ShippingDestination theDest;

        string theZone;

        do

        {

            // get destination zone

            Console.WriteLine("What is the destination zone");

            theZone = Console.ReadLine();

            // if the User wrote "Exit" terminate the program,

            // other wise continue

            if (!theZone.Equals("exit"))

            {

                // given the zone, retrieve associated shipping

                theDest = ShippingDestination.getDestinationInfo(theZone);

                // if there's no associated info, then the User entered

                // an invalid zone, otherwise continue

                if(theDest != null)

                {

                    // ask for the price and convert the string to double number

                    Console.WriteLine("What is the item price?");

                    string thePriceStr = Console.ReadLine();

                    double itemPrice = double.Parse(thePriceStr);

                    // Each ShippingDestination object has a function called calcFees

                    // use that as the delegate for calculating the fee

                    theDel = theDest.calcFees;

                    // For the high-risk Zones, we tack on the delegate that adds more

                    if (theDest.m_isHighRisk)

                    {

                        // Declaring anonymous delegate

                        theDel += delegate (double price, ref double itemFee)

                        {

                            itemFee += 25;

                        };

                    }

                    // now all that is left to do is a call the delegate and output

                    // the shipping fee to the Console

                    double theFee = 0.0;

                    theDel(itemPrice, ref theFee);

                    Console.WriteLine("The shipping fees are: {0} $",theFee);

                    Console.WriteLine("The whole charge for item is: {0} $", itemPrice+theFee);

                    Console.WriteLine();

                }

                else

                {

                    Console.WriteLine();

                    Console.WriteLine("Hmm, you seem to have entered an unknown destination");

                    Console.WriteLine("Would you like to try again?");

                    Console.WriteLine();

                }

            }

        } while (theZone != "exit");

    }

}

​

// this is a base class that is used as a foundation

// for each of the destination zones

​

abstract class ShippingDestination

{

    public bool m_isHighRisk;

    public virtual void calcFees (double price, ref double fee) { }

    //This static method returns a actual ShippingDestination object

    //given the name of the destination, or null if non exists

    public static ShippingDestination getDestinationInfo(string dest)

    {

        if (dest.Equals("Zone1"))

        {

            return new Dest_Zone1();

        }

        if (dest.Equals("Zone2"))

        {

            return new Dest_Zone2();

        }

        if (dest.Equals("Zone3"))

        {

            return new Dest_Zone3();

        }

        if (dest.Equals("Zone4"))

        {

            return new Dest_Zone4();

        }

        if (dest.Equals("Zone5"))

        {

            return new Dest_Zone5();

        }

        return null;

    }

}

​

internal class Dest_Zone1 : ShippingDestination

{

   public Dest_Zone1()

   {

   m_isHighRisk = false;

   }

   public override void calcFees(double price, ref double fee)

   {

   fee = price * 0.25;

   }

}

​

internal class Dest_Zone2 : ShippingDestination

{

   public Dest_Zone2()

   {

   m_isHighRisk = true;

   }

   public override void calcFees(double price, ref double fee)

   {

   fee = price * 0.12;

   }

}

​

internal class Dest_Zone3 : ShippingDestination

{

   public Dest_Zone3()

   {

   m_isHighRisk = false;

   }

   public override void calcFees(double price, ref double fee)

   {

   fee = price * 0.08;

   }

}

​

internal class Dest_Zone4 : ShippingDestination

{

   public Dest_Zone4()

   {

   m_isHighRisk = true;

   }

   public override void calcFees(double price, ref double fee)

   {

   fee = price * 0.04;

   }

}

​

internal class Dest_Zone5 : ShippingDestination

{

   public Dest_Zone5()

   {

   m_isHighRisk = false;

   }

   public override void calcFees(double price, ref double fee)

   {

   fee = price * 0.15;

   }

}