按照C++ Primer書里寫的程式運行不了(在第20頁)，好像編譯器認不出成員函式（我是初學者）
#include <iostream>
#include "Sales_item.h"
int main() {
Sales_item item1, item2;
std::cin >> item1 >> item2;
if (item1.isbn() == item2.isbn()） {//把這邊代表函式的括號刪掉，寫成if (item1.isbn == item2.isbn）{就沒事了。。。
std::cout << item1 + item2 << std::endl;
return 0;
}
else {
std::cerr << "Data must refer to the same ISBN" << std::endl;
return -1;
}
}
這個是報錯
這個是參考的頭檔案
#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
想不明白為什么，請各位大佬指點一下
uj5u.com熱心網友回復：
isbn是個成員欄位，不是函式吧uj5u.com熱心網友回復：
#include <iostream>
#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) {}
std::string Sales_item::get_isbn() const
{
return isbn;
}
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 //SALESITEM_H
int main() {
Sales_item item1, item2;
std::cin >> item1 >> item2;
// if (item1.isbn == item2.isbn) {
if (item1.get_isbn() == item2.get_isbn()) {
std::cout << item1 + item2 << std::endl;
return 0;
}
else {
std::cerr << "Data must refer to the same ISBN" << std::endl;
return -1;
}
}
uj5u.com熱心網友回復：
item1.isbn() == item2.isbn()===============
isbn()沒有這個函式，只有這個自變數
轉載請註明出處，本文鏈接：https://www.uj5u.com/houduan/256029.html
標籤：C++ 語言
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