我正在使用电子书Primer c ++，我已经达到了这个章节，我应该创建一个程序，输入2本书的名称，价格和销售数量，并输出收益/平均销售价格的总和。 我的任务是粘贴他们在项目中的新类中给我的代码，而不是在我的主类中使用它，我无法编译代码编译器（代码块和VS express）在我做的时都显示错误
（请注意，这是在我开始编写自己的任何代码之前，所以它可能是我创建类或编译器的方式的问题） （要创建一个我点击File＆gt; New class的类 - 将它命名为Sales_item并完成，比它问我是否想将它与我正在处理的项目相关联{空项目只有空主方法}我点击是并粘贴代码）
/*
* This file contains code from "C++ Primer, Fifth Edition", by Stanley B.
* Lippman, Josee Lajoie, and Barbara E. Moo, and is covered under the
* copyright and warranty notices given in that book:
*
* "Copyright (c) 2013 by Objectwrite, Inc., Josee Lajoie, and Barbara E. Moo."
*
*
* "The authors and publisher have taken care in the preparation of this book,
* but make no expressed or implied warranty of any kind and assume no
* responsibility for errors or omissions. No liability is assumed for
* incidental or consequential damages in connection with or arising out of the
* use of the information or programs contained herein."
*
* Permission is granted for this code to be used for educational purposes in
* association with the book, given proper citation if and when posted or
* reproduced.Any commercial use of this code requires the explicit written
* permission of the publisher, Addison-Wesley Professional, a division of
* Pearson Education, Inc. Send your request for permission, stating clearly
* what code you would like to use, and in what specific way, to the following
* address:
*
* Pearson Education, Inc.
* Rights and Permissions Department
* One Lake Street
* Upper Saddle River, NJ 07458
* Fax: (201) 236-3290
*/
/* This file defines the Sales_item class used in chapter 1.
* The code used in this file will be explained in
* Chapter 7 (Classes) and Chapter 14 (Overloaded Operators)
* Readers shouldn't try to understand the code in this file
* until they have read those chapters.
*/
#ifndef SALESITEM_H
// we're here only if SALESITEM_H has not yet been defined
#define SALESITEM_H
// Definition of Sales_item class and related functions goes here
#include <iostream>
#include <string>
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.isbn(); }
// nonmember binary operator: must declare a parameter for each operand
Sales_item operator+(const Sales_item&, const Sales_item&);
inline bool
operator==(const Sales_item &lhs, const Sales_item &rhs)
{
// must be made a friend of Sales_item
return lhs.units_sold == rhs.units_sold &&
lhs.revenue == rhs.revenue &&
lhs.isbn() == rhs.isbn();
}
inline bool
operator!=(const Sales_item &lhs, const Sales_item &rhs)
{
return !(lhs == rhs); // != defined in terms of operator==
}
// assumes that both objects refer to the same ISBN
Sales_item& Sales_item::operator+=(const Sales_item& rhs)
{
units_sold += rhs.units_sold;
revenue += rhs.revenue;
return *this;
}
// assumes that both objects refer to the same ISBN
Sales_item
operator+(const Sales_item& lhs, const Sales_item& rhs)
{
Sales_item ret(lhs); // copy (|lhs|) into a local object that we'll return
ret += rhs; // add in the contents of (|rhs|)
return ret; // return (|ret|) by value
}
std::istream&
operator>>(std::istream& in, Sales_item& s)
{
double price;
in >> s.bookNo >> s.units_sold >> price;
// check that the inputs succeeded
if (in)
s.revenue = s.units_sold * price;
else
s = Sales_item(); // input failed: reset object to default state
return in;
}
std::ostream&
operator<<(std::ostream& out, const Sales_item& s)
{
out << s.isbn() << " " << s.units_sold << " "
<< s.revenue << " " << s.avg_price();
return out;
}
double Sales_item::avg_price() const
{
if (units_sold)
return revenue/units_sold;
else
return 0;
}
#endif
这就是错误 -
||=== Build: Debug in Sales_item (compiler: GNU GCC Compiler) ===|
include\Sales_item.h|56|warning: defaulted and deleted functions only available with -std=c++11 or -std=gnu++11|
include\Sales_item.h|70|warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11|
include\Sales_item.h|71|warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11|
include\Sales_item.h|45|error: constructor required before non-static data member for 'Sales_item::units_sold' has been parsed|
include\Sales_item.h|45|error: constructor required before non-static data member for 'Sales_item::revenue' has been parsed|
C:\Users\Tomer\Desktop\C++\Code\Sales_item\src\Sales_item.cpp|3|error: definition of explicitly-defaulted 'Sales_item::Sales_item()'|
include\Sales_item.h|56|error: 'Sales_item::Sales_item()' explicitly defaulted here|
C:\Users\Tomer\Desktop\C++\Code\Sales_item\src\Sales_item.cpp|8|error: definition of implicitly-declared 'Sales_item::~Sales_item()'|
||=== Build failed: 5 error(s), 3 warning(s) (0 minute(s), 0 second(s)) ===|
抱歉英语不好。
答案 0 :(得分：0)
也许你应该让你的编译器或IDE支持c ++ 11，因为代码使用了一些新的关键字。我测试它，它适用于c ++ 11。