The library requires a class to store information about a book. Set up a class to hold data including title, author, year of publication, and a boolean variable to indicate if the book is in the library or if the book has been taken out. Create a method to load the data for one book. Create another method to display the data for a book. Create another method to check if a book is in the library or not. Write a main program to test your methods. 用c++

以下是一个可能的类定义，包括所需的数据成员和方法：

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

class Book {
private:
    string title;
    string author;
    int year;
    bool in_library;

public:
    void load_data(string t, string a, int y, bool l) {
        title = t;
        author = a;
        year = y;
        in_library = l;
    }

    void display_data() {
        cout << "Title: " << title << endl;
        cout << "Author: " << author << endl;
        cout << "Year of publication: " << year << endl;
        if (in_library) {
            cout << "In library: Yes" << endl;
        } else {
            cout << "In library: No" << endl;
        }
    }

    bool is_in_library() {
        return in_library;
    }
};

int main() {
    Book b1;
    b1.load_data("The Catcher in the Rye", "J.D. Salinger", 1951, true);
    b1.display_data();

    if (b1.is_in_library()) {
        cout << "This book is in the library." << endl;
    } else {
        cout << "This book has been taken out." << endl;
    }

    return 0;
}

这个程序演示了如何创建一个 `Book` 类的实例，使用 `load_data` 方法为其加载数据，使用 `display_data` 方法显示数据，并使用 `is_in_library` 方法检查书籍是否在库中。在这个例子中，`Book` 类只有一个实例，但在实际情况下，可以创建多个不同的 `Book` 对象，每个对象表示不同的书籍。