Chapter 15.3, Problem 11STE

Explanation of Solution

Program:

File name: sale.h

//include libraries

#ifndef SALE_H

#define SALE_H

#include <iostream>

using namespace std;

//using the namespace

namespace salesavitch

{

    //create a class

    class Sale

    {

        //define access specifier

        public:

        //declare the constructors

        Sale();

        Sale(double thePrice);

        //define required methods

        double bill() const;

        double savings(const Sale& other) const;

        //define access specifier

        protected:

        //declare required variables

        double price;

    };

    //define an overloaded method

    bool operator <(const Sale& first, const Sale&

  second);

}

#endif // SALE_H

File name: discount.h

//include libraries

#ifndef DISCOUNTSALE_H

#define DISCOUNTSALE_H

#include "sale.h"

//using the namespace

namespace salesavitch

{

    //create a class

    class DiscountSale : public Sale

    {

        //define access specifier

        public:

        //declare the constructors

        DiscountSale();

        DiscountSale(double the_price, double the_discount);

        //Discount is expressed as a percent of the price.

        virtual double bill() const;

        //define access specifier

        protected:

        //declare required variable

        double discount;

    };

}

#endif //DISCOUNTSALE_H

File name: sale.cpp

//include libraries

#include "sale.h"

//using the namespace

namespace salesavitch

{

    //define a constructor

  Sale::Sale() : price(0)

  {}

    //define a constructor

  Sale::Sale(double the_price) : price(the_price)

  {}

    //declare a method

  double Sale::bill() const

  {

        //return statement

  return price;

  }

    //declare a method

  double Sale::savings(const Sale& other) const

  {

        //return statement

  return ( bill() - other...