Windows 7下居然提示

#include <iostream>
#include <cstring>
using namespace std;

class Books
{
    private:
        float Price;
        string Author;
    public:
        Books(float price, string author);
        void ShowInfo();
        Books& operator =(const Books &bookname);
};

Books& Books::operator = (const Books &bookname)
{
    if (&bookname == this)
        return *this;
    else
    {
        Books temp(bookname.Price, bookname.Author);
        return temp;
    }
}

Books::Books(float price, string author)
{
    Price = price;
    Author = author;
}

void Books::ShowInfo()
{
    cout << "Book Price" << '\t' << Price << endl;
    cout << "Book Author" << '\t' << Author << endl;
}

int main()
{
    Books APEU(67, "Bob");
    APEU.ShowInfo();
    return 0;
}

void Books::ShowInfo()
{
    cout << "Book Price" << '\t' << Price << endl;
    cout << "Book Author" << '\t' << Author.c_str() << endl;
}

注意红色的地方

你把#include <cstring>改成#include <string>就没有问题了

谢谢。可是还是不能通过

Books& Books::operator = (const Books &bookname)
{
    if (&bookname == this)
        return *this;
    else
    {
        Books temp(bookname.Price, bookname.Author);
        return temp;
    }
}你这段代码，有问题，容易造成运行错误，你返回的一个临时对象的引用！函数返回的时候，对象都释放了，你还返回一个对象的引用

我该了一下，可还是不对

#include <iostream>
#include <string>
using namespace std;

class Books
{
    private:
        float Price;
        string Author;
    public:
        Books(float price, string author);
        void ShowInfo();
        Books operator =(const Books &bookname);
};

Books Books::operator = (const Books &bookname)
{
    if (&bookname == this)
        return *this;
    else
        return Books(bookname.Price, bookname.Author); //这里
}

Books::Books(float price, string author)
{
    Price = price;
    Author = author;
}

void Books::ShowInfo()
{
    cout << "Book Price" << '\t' << Price << endl;
    cout << "Book Author" << '\t' << Author << endl;
}

int main()
{
    Books APEU(67, "Bob");
    APEU.ShowInfo();
    return 0;
}

2楼的没问题，试过了

六楼的代码我有DEV-C++试了下，管用。只是在return 0;前加了个system("pause");
输出的是：
Book price   67
Book Author  Bob

试了。 把cstring改为string输出正常。有可能是你编译环境的问题！

程序应该没有问题，和你的IDE有关吧？
提一个建议，建议构造函数这样写，
  Books(float price, string author):Price(price), Author(author){};