62 lines
1.5 KiB
C++
62 lines
1.5 KiB
C++
#ifndef EXERCISE7_11_H_
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#define EXERCISE7_11_H_
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#include <iostream>
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#include <string>
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using std::istream;
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using std::ostream;
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using std::endl;
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using std::string;
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struct Sales_data {
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string bookNo;
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unsigned units_sold;
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double revenue;
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//constructors
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Sales_data() { units_sold = 0, revenue = 0.0; }
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Sales_data(istream &is);
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Sales_data(string isbn) : bookNo(isbn) {};
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Sales_data(string isbn, unsigned n, double price) : bookNo(isbn), units_sold(n), revenue(n * price) {};
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string isbn() const { return bookNo; }
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double avg_price() const { return revenue / units_sold; }
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Sales_data& combine(Sales_data const &data); //behave same as the `+=` operator, thus return a left-value
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};
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//constructors
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Sales_data::Sales_data(istream &is){
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double price;
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is >> bookNo >> units_sold >> price;
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revenue = price * units_sold;
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}
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Sales_data& Sales_data::combine(Sales_data const &data) {
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units_sold += data.units_sold;
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revenue += data.revenue;
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return *this;
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}
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Sales_data add(Sales_data const &one, Sales_data const &two) {
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Sales_data res = one;
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return res.combine(two);
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}
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istream& read(istream &is, Sales_data &data) {
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is >> data.bookNo;
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is >> data.units_sold;
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is >> data.revenue;
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return is;
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}
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ostream& print(ostream &os, Sales_data const data) {
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os << "book number: " << data.bookNo << endl;
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os << "units sold: " << data.units_sold << endl;
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os << "total revenue: " << data.revenue << endl;
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os << "averge price: " << data.avg_price(); // no endl at the end
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return os;
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}
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#endif
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