Frammenti di codice proiettati a lezione

Di seguito i frammenti di codice proiettati oggi a lezione.

struct Sales_data{

    Sales_data(istream&);

/*  Sales_data();

    Sales_data(const string&);

    Sales_data(const string&, unsigned, double); */

    

    Sales_data(string="----", unsigned=0, double=0.0);

    

    string isbn() const {return bookNo;}

    Sales_data& combine(const Sales_data&);

    double avg_price() const;

    

    ostream& stampa(ostream&);

    istream& leggi(istream&);

    

    string bookNo;

    unsigned units;

    double revenue;

};

Sales_data add(const Sales_data&, const Sales_data&);

ostream& print(ostream&, const Sales_data&);

istream& read(istream&, Sales_data&);

/*Sales_data::Sales_data(){

    bookNo="----";

    units=0;

    revenue=0.0;

}*/

Sales_data::Sales_data(string s, unsigned n, double p):bookNo(s), units(n), revenue(n*p){;}

Sales_data::Sales_data():revenue(0.0), units(0){;}

/*Sales_data::Sales_data(const string& s){

    bookNo=s;

    units=0;

    revenue=0.0;

}*/

Sales_data::Sales_data(const string& s) : bookNo(s), units(0), revenue(0.0) {;}

/*

Sales_data::Sales_data(const string& s, unsigned n, double p){

    bookNo = s;

    units = n;

    revenue = n*p;

}

*/

Sales_data::Sales_data(const string& s, unsigned n, double p):bookNo(s), units(n), revenue(n*p) {;}

Sales_data::Sales_data(istream& in){

    read(in, *this);

}

double Sales_data::avg_price() const {

    if(units)

        return revenue/units;

    else

        return 0;

}

istream& leggi(istream&);

Sales_data add(const Sales_data& a, const Sales_data& b){

    Sales_data sum = a;

    sum.combine(b);

    return sum;

}

Sales_data& Sales_data::combine(const Sales_data& r){

    if(r.isbn()==isbn()){

        this->units += r.units;

        this->revenue += r.revenue;

    }

    return *this;

}

istream& read(istream& in, Sales_data& s){

    double price;

    in >> s.bookNo >> s.units >> price;

    s.revenue = s.units*price;

    return in;

}

istream& Sales_data::leggi(istream& in){

    double price;

    in >> bookNo >> units >> price;

    revenue = units*price;

    return in;

}

ostream& print(ostream& out, const Sales_data& s){

    out << s.isbn() << " " << s.units << " " << s.revenue << " " << s.avg_price();

    return out;

}

ostream& Sales_data::stampa(ostream& out) {

    out << isbn() << " " << units << " " << revenue << " " << avg_price();

    return out;

}