定义一个Book类，该类定义中包括：
数据成员:bookname, price, number(存书数量)
成员函数:
　　　 display()　 //显示图书的情况‘
　　　 borrow()　 //将存书量减1,并显示当前存书数量
　　　 restore()　 //将存书量加1,并显示当前存书数量
在main()函数中，要求创建多种图书数量，并且对该图书进行简单的显示、借阅和归还管理。(Define a Book class that includes:
Data members: bookname, price, number (the number of books)
Member functions:
(display) / / display the situation of books "
(borrow) / / storage minus 1, and displays the current number of books
(restore) / / add storage 1, and displays the current number of books
In the main () function, a number of books are required to be created and a simple display, loan, and return management of the book is made.)