ex2.42_2.cpp

#include <iostream>
#include "Sales_data.h"

int main()
{
  Sales_data book1, book2;
  double price1, price2;
  std::cin >> book1.bookNo >> book1.units_sold >> price1;
  std::cin >> book2.bookNo >> book2.units_sold >> price2;
  book1.CalcRevenue(price1);
  book2.CalcRevenue(price2);

  if (book1.bookNo == book2.bookNo)
  {
    book1.AddData(book2);
    book1.Print();

    return 0;
  }
  else
  {
    std::cerr << "Data must refer to same ISBN" << std::endl;
    return -1;  // indicate failure
  }
}