Sales_data.cpp

#include "Sales_data.h"

Sales_data &Sales_data::combine(const Sales_data &rhs) {
	units_sold += rhs.units_sold;
	revenue += rhs.revenue;
	return *this;
}

double Sales_data::avg_price() const {
	if (units_sold)
		return revenue / units_sold;
	else
		return 0;
}

// NONMEMBER FUNCTIONS

Sales_data add(const Sales_data &lhs, const Sales_data &rhs) {
	Sales_data sum = lhs;
	sum.combine(rhs);
	return sum;
}

std::istream &read(std::istream &is, Sales_data &item) {
	double price = 0.0;
	is >> item.bookNo >> item.units_sold >> price;
	item.revenue = item.units_sold * price;
	return is;
}

std::ostream &print(std::ostream &os, const Sales_data &item) {
	os << item.isbn() << " " << item.units_sold << " " << item.revenue << " " << item.avg_price();
	return os;
}