ex7_41.h

//
//  ex7_41.h
//  Exercise 7.41 
//
//  Created by pezy on 11/20/14.
//
//  @See ex7_26.h
//  @Add 1. use delegating constructors
//       2. add a statement to the body of each of the constructors that prints a message whether it is executed. 

#ifndef CP5_ex7_41_h
#define CP5_ex7_41_h

#include <string>
#include <iostream>

class Sales_data {
    friend std::istream &read(std::istream &is, Sales_data &item);
    friend std::ostream &print(std::ostream &os, const Sales_data &item);
    friend Sales_data add(const Sales_data &lhs, const Sales_data &rhs);

public:
    Sales_data(const std::string &s, unsigned n, double p):bookNo(s), units_sold(n), revenue(n*p)
    { std::cout << "Sales_data(const std::string&, unsigned, double)" << std::endl; }
    
    Sales_data() : Sales_data("", 0, 0.0f)
    { std::cout << "Sales_data()" << std::endl; }
    
    Sales_data(const std::string &s) : Sales_data(s, 0, 0.0f)
    { std::cout << "Sales_data(const std::string&)" << std::endl; }
    
    Sales_data(std::istream &is);

    std::string isbn() const { return bookNo; }
    Sales_data& combine(const Sales_data&);
    
private:
    inline double avg_price() const;        

private:
    std::string bookNo;
    unsigned units_sold = 0;
    double revenue = 0.0;
};

inline
double Sales_data::avg_price() const
{
    return units_sold ? revenue/units_sold : 0;
}

// declarations for nonmember parts of the Sales_data interface.
std::istream &read(std::istream &is, Sales_data &item);
std::ostream &print(std::ostream &os, const Sales_data &item);
Sales_data add(const Sales_data &lhs, const Sales_data &rhs);

#endif