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sleeplacker 2014-01-25
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我记得我是改过那个头文件的
我运行没问题，你看看是你哪里错了
Sales_item.h:
#ifndef SALESITEM_H
#define SALESITEM_H
#include <iostream>
#include <string>
class Sales_item
{
public:
Sales_item(const std::string &book):isbn(book),units_sold(0),revenue(0.0){}
Sales_item(std::istream &is){ is >> *this;}
friend std::istream& operator>>(std::istream &,Sales_item &);
friend std::ostream& operator<<(std::ostream &,const Sales_item &);
public:
Sales_item & operator+=(const Sales_item&);
public:
double avg_price() const;
bool same_isbn(const Sales_item &rhs)const
{
return isbn == rhs.isbn;
}
Sales_item():units_sold(0),revenue(0.0){}
public:
std::string isbn;
unsigned units_sold;
double revenue;
};
using std::istream;
using std::ostream;
Sales_item operator+(const Sales_item &,const Sales_item &);
inline bool operator==(const Sales_item &lhs,const Sales_item &rhs)
{
return lhs.units_sold == rhs.units_sold && lhs.revenue == rhs.revenue && lhs.same_isbn(rhs);
}
inline bool operator!=(const Sales_item &lhs,const Sales_item &rhs)
{
return !(lhs == rhs);
}
inline Sales_item & Sales_item::operator +=(const Sales_item &rhs)
{
units_sold += rhs.units_sold;
revenue += rhs.revenue;
return *this;
}
inline Sales_item operator+(const Sales_item &lhs,const Sales_item &rhs)
{
Sales_item ret(lhs);
ret += rhs;
return ret;
}
inline istream& operator>>(istream &in,Sales_item &s)
{
double price;
in >> s.isbn >> s.units_sold >> price;
if(in)
s.revenue = s.units_sold * price;
else
s = Sales_item();
return in;
}
inline ostream& operator<<(ostream &out,const Sales_item &s)
{
out << s.isbn << " " <<s.units_sold << " " << s.revenue << " " << s.avg_price();
return out;
}
inline double Sales_item::avg_price() const
{
if(units_sold)
return revenue/units_sold;
else
return 0;
}
#endif #include <iostream>
#include "Sales_item.h"
int main()
{
Sales_item total; // variable to hold data for the next tansaction
// read the first transaction and ensure that there are data to process
if (std::cin >> total) {
Sales_item trans; // variable to hold the running sum
// read and process the remaining transactions
while (std::cin >> trans) {
// if we're still processing 0the same book
if (total.isbn == trans.isbn) {
total += trans; // update the running total
}
else {
// print result for the previous book
std::cout << total << std::endl;
total = trans; // total now refers to the next book
}
}
std::cout << total << std::endl; //print the last transaction
} else {
// no input!warn the user
std::cerr << "No data?!" << std::endl;
return -1; //indicate failure
}
return 0;
}
arthurzhuyong 2014-01-25
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std::string isbn;
// operations on Sales_item objects
std::string isbn() const { return bookNo; }
class Sales_item {
// these declarations are explained section 7.2.1, p. 270
// and in chapter 14, pages 557, 558, 561
friend std::istream& operator>>(std::istream&, Sales_item&);
friend std::ostream& operator<<(std::ostream&, const Sales_item&);
friend bool operator<(const Sales_item&, const Sales_item&);
friend bool
operator==(const Sales_item&, const Sales_item&);
public:
// constructors are explained in section 7.1.4, pages 262 - 265
// default constructor needed to initialize members of built-in type
Sales_item() = default;
Sales_item(const std::string &book): bookNo(book) { }
Sales_item(std::istream &is) { is >> *this; }
public:
// operations on Sales_item objects
// member binary operator: left-hand operand bound to implicit this pointer
Sales_item& operator+=(const Sales_item&);
// operations on Sales_item objects
std::string isbn() const { return bookNo; }
double avg_price() const;
// private members as before
private:
std::string bookNo; // implicitly initialized to the empty string
unsigned units_sold = 0; // explicitly initialized
double revenue = 0.0;
};
// used in chapter 10
inline
bool compareIsbn(const Sales_item &lhs, const Sales_item &rhs)
{ return lhs.isbn() == rhs.u013529401 2014-01-25
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有的啊
u013529401 2014-01-25
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这个我有的，应该不是这个问题
JPF1024 2014-01-25
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网上找的.放在同一个文件夹.
#ifndef SALESITEM_H
#define SALESITEM_H
#include <iostream>
#include <string>
class Sales_item
{
public:
Sales_item(const std::string &book):isbn(book),units_sold(0),revenue(0.0){}
Sales_item(std::istream &is){ is >> *this;}
friend std::istream& operator>>(std::istream &,Sales_item &);
friend std::ostream& operator<<(std::ostream &,const Sales_item &);
public:
Sales_item & operator+=(const Sales_item&);
public:
double avg_price() const;
bool same_isbn(const Sales_item &rhs)const
{
return isbn == rhs.isbn;
}
Sales_item():units_sold(0),revenue(0.0){}
public:
std::string isbn;
unsigned units_sold;
double revenue;
};
using std::istream;
using std::ostream;
Sales_item operator+(const Sales_item &,const Sales_item &);
inline bool operator==(const Sales_item &lhs,const Sales_item &rhs)
{
return lhs.units_sold == rhs.units_sold && lhs.revenue == rhs.revenue && lhs.same_isbn(rhs);
}
inline bool operator!=(const Sales_item &lhs,const Sales_item &rhs)
{
return !(lhs == rhs);
}
inline Sales_item & Sales_item::operator +=(const Sales_item &rhs)
{
units_sold += rhs.units_sold;
revenue += rhs.revenue;
return *this;
}
inline Sales_item operator+(const Sales_item &lhs,const Sales_item &rhs)
{
Sales_item ret(lhs);
ret += rhs;
return ret;
}
inline istream& operator>>(istream &in,Sales_item &s)
{
double price;
in >> s.isbn >> s.units_sold >> price;
if(in)
s.revenue = s.units_sold * price;
else
s = Sales_item();
return in;
}
inline ostream& operator<<(ostream &out,const Sales_item &s)
{
out << s.isbn << "\t" <<s.units_sold << "\t" << s.revenue << "\t" << s.avg_price();
return out;
}
inline double Sales_item::avg_price() const
{
if(units_sold)
return revenue/units_sold;
else
return 0;
}
#endif
arthurzhuyong 2014-01-25
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有那个Sales_item.h ??
