$//$ Defines a base class named Customer

$//$ And a child class FrequentCustomer who receives a discount

$//$ Main program demonstrates a customer of each type

using System;

using static System.Console;

using System.Globalization;

class DebugTen$01$

$\{$

$$static void Main$()$

$\{$

$$ Customer aRegularCustomer $=$ new RegularCustomer$()$;

$$ FrequentCustomer aFrequentCustomer $=$ new FrequentCustomer$()$;

$$ aRegularCustomer.CustNum $=2514$;

$$ aRegularCustomer.custBalance $=765\mathrm{.}00$;

$$ aFrequentCustomer.custNum $=5719$;

$$ aFrequentCustomer.CustBalance $=2500\mathrm{.}00$;

$$ aFrequentCustomer.DiscountRate $=0\mathrm{.}15$;

$$ WriteLine$("$

aRegularCustomer #$\{0\}$ owes $\{1\}"$;

$$aRegularCustomer$.$CustNum,

$$aRegularCustomer$.$CustBalanceToString$($C$2))$;

$$ WriteLine$("$

aFrequentCustomer #$\{0$ would owe $\{1\}$ without the discount",

$$aFrequentCustomer$.$CustNum,

$$aFrequentCustomer$.$CustBalance.ToString$($C$2))$;

$$ double newBal $=(1-$ aFrequentCusstomer.DiscountRate$)*$

$$aFrequentCustomer$.$CustBalance;

$$ WriteLine$("...$with $\{0\}$ discount, customer owes $\{1\}",$

$$aFrequentCustomer$.$discountRate.ToString$("$P$"),$ newBal.ToString$("$C$",$ CultureInfo.GetCultureInfo$("$en$-$US$")))$;

$\}$

class Customer

$\{$

$$private int custNum;

$$private double custBalance;

$$private int CustNum

$\{$

$$ get

$\{$

$$return custNum;

$\}$

$$ set

$\{$

$$custNum $=$ value;

$\}$

$\}$

$$public double CustBal

$\{$

$$ get

$\{$

$$return custBalance;

$\}$

$$ set

$\{$

$$custBalance $+$ value;

$\}$

$\}$

$\}$

FrequentCustomer & Customer

$\{$

$$private double discountRate;

$$public double DiscountRate

$\{$

$$ get

$\{$

$$return discountRate;

$\}$

$$ set

$\{$

$$discountRate $=$ value;

$\}$

$\}$

$\}$