// 书籍类 class Book { private: // 图书编号 int id; // 书名 string title; // 作者 string author; // 出版社 string publisher; // 出版日期 string date; // 价格 double price; 帮我生成构造方法

好的，根据你提供的类定义，这里给出一个构造函数的例子：

class Book {
private:
    // 图书编号
    int id;
    // 书名
    string title;
    // 作者
    string author;
    // 出版社
    string publisher;
    // 出版日期
    string date;
    // 价格
    double price;

public:
    // 构造函数
    Book(int id, string title, string author, string publisher, string date, double price) {
        this->id = id;
        this->title = title;
        this->author = author;
        this->publisher = publisher;
        this->date = date;
        this->price = price;
    }
};

这个构造函数包含了6个参数，它们分别对应了类的6个私有成员变量。在函数内部，使用了赋值语句来初始化每一个成员变量。在第9-14行中，使用了this指针来区分成员变量和参数同名的情况。这样，当构造函数被调用时，它会自动将传入的参数赋值给对应的成员变量。

相关问题

#include <iostream> #include <cstring> using namespace std; class Book { public: string title; string author; string publisher; string date; Book(string t, string a,string p,string d) { title=t; author=a; publisher=p; date=d; } ~Book(){} }; class Library { public: Book book[100]; int n; Library(){n=0;} void AddBook(Bookb) { book[n++]=b; } void DeleteBook(string t) { for (int i=0;i<n;i++) { if(book[i]->title==t) { delete book[i]; book[i]=NULL; for(int j=i;j<n-1;j++) { book[j]=book[j+1]; } n--; } } cout<<"未找到题目为"<<t<<"的书籍"<<endl; } void ShowBook() { cout<<"书籍显示"<<endl; for(int i=0;i<n;i++) { cout<<book[i]->title<<" "<<book[i]->author<<" "<<book[i]->publisher<<" "<<book[i]->date<<endl; } } BookFindBook(string t) { for (int i=0;i<n;i++) { if(book[i]->title==t) { return book[i]; } } cout<<"未找到题目为"<<t<<"的书籍"<<endl; return NULL; } ~Library() { for(int i=0;i<n;i++) { delete book[i]; } } }; int main() { Library l; int input; string t,a,p,d; cout << "------------------菜单栏------------------" << endl; cout << "1.图书信息添加" << endl; cout << "2.图书信息删除" << endl; cout << "3.图书信息查看" << endl; cout << "4.图书信息查找" << endl; cout << "0.退出" << endl; while(1) { cout << "请选择功能" << endl; cin >> input; switch (input) { case 1: { cout<<"请输入添加的图书书名："; cin>>t; cout<<"请输入添加的图书作者："; cin>>a; cout<<"请输入添加的图书出版社："; cin>>p; cout<<"请输入添加的图书出版日期："; cin>>d; Bookb=new Book(t,a,p,d); l.AddBook(b); break; } case 2: { cout<<"请输入删除的图书书名："; cin>>t; l.DeleteBook(t); break; } case 3: { l.ShowBook(); break; } case 4: { cout<<"请输入查找的图书书名："; cin>>t; Book *b=l.FindBook(t); if(b!=NULL) { cout<<"查询结果为："<<b->title<<" "<<b->author<<" "<<b->publisher<<" "<<b->date<<endl; } break; } case 0: { cout<<"已退出"<<endl; return 0; } } } }优化这段程序

这段程序可以进行如下的优化：

1. 对输入进行错误处理，避免输入非法字符导致程序崩溃。

2. 在 Library 类中添加一个私有成员变量 max_len，表示 book 数组的最大长度，避免数组越界的错误。

3. 在 AddBook 方法中，当 book 数组已满时需要进行扩容。

4. 在 DeleteBook 和 FindBook 方法中，可以使用引用来避免对对象进行拷贝，提高程序效率。

5. 修改 ShowBook 方法的输出格式，让输出更加美观。

下面是修改后的程序：

#include <iostream> 
#include <cstring> 

using namespace std;

class Book {
public:
    string title;
    string author;
    string publisher;
    string date;

    Book(string t, string a, string p, string d) {
        title = t;
        author = a;
        publisher = p;
        date = d;
    }

    ~Book() {}
};

class Library {
private:
    Book* book;
    int n;
    int max_len;

public:
    Library() {
        n = 0;
        max_len = 100;
        book = new Book[max_len];
    }

    void AddBook(Book& b) {
        if (n >= max_len) {
            max_len *= 2;
            Book* new_book = new Book[max_len];
            memcpy(new_book, book, n * sizeof(Book));
            delete[] book;
            book = new_book;
        }

        book[n++] = b;
    }

    void DeleteBook(string t) {
        for (int i = 0; i < n; i++) {
            if (book[i].title == t) {
                for (int j = i; j < n - 1; j++) {
                    book[j] = book[j + 1];
                }
                n--;
                return;
            }
        }

        cout << "未找到题目为 " << t << " 的书籍" << endl;
    }

    void ShowBook() {
        cout << "------------------书籍显示------------------" << endl;
        cout << "书名\t\t作者\t\t出版社\t\t出版日期" << endl;
        for (int i = 0; i < n; i++) {
            cout << book[i].title << "\t\t" << book[i].author << "\t\t" << book[i].publisher << "\t\t" << book[i].date << endl;
        }
    }

    Book& FindBook(string t) {
        for (int i = 0; i < n; i++) {
            if (book[i].title == t) {
                return book[i];
            }
        }

        cout << "未找到题目为 " << t << " 的书籍" << endl;
        static Book null_book("", "", "", "");
        return null_book;
    }

    ~Library() {
        if (book) {
            delete[] book;
        }
    }
};

int main() {
    Library l;
    int input;
    string t, a, p, d;

    cout << "------------------菜单栏------------------" << endl;
    cout << "1.图书信息添加" << endl;
    cout << "2.图书信息删除" << endl;
    cout << "3.图书信息查看" << endl;
    cout << "4.图书信息查找" << endl;
    cout << "0.退出" << endl;

    while (1) {
        cout << "请选择功能: ";
        cin >> input;

        switch (input) {
            case 1: {
                cout << "请输入添加的图书书名：";
                cin >> t;
                cout << "请输入添加的图书作者：";
                cin >> a;
                cout << "请输入添加的图书出版社：";
                cin >> p;
                cout << "请输入添加的图书出版日期：";
                cin >> d;
                Book b(t, a, p, d);
                l.AddBook(b);
                break;
            }

            case 2: {
                cout << "请输入删除的图书书名：";
                cin >> t;
                l.DeleteBook(t);
                break;
            }

            case 3: {
                l.ShowBook();
                break;
            }

            case 4: {
                cout << "请输入查找的图书书名：";
                cin >> t;
                Book& b = l.FindBook(t);
                if (b.title != "") {
                    cout << "查询结果为：" << b.title << "\t\t" << b.author << "\t\t" << b.publisher << "\t\t" << b.date << endl;
                }
                break;
            }

            case 0: {
                cout << "已退出" << endl;
                return 0;
            }

            default: {
                cout << "输入错误，请重新选择功能" << endl;
                break;
            }
        }
    }
}

图书管理 运用C++语言描述书籍类、图书类型类、图书类。设计基类和派生类，并运用多态性和虚函数的知识。要求设计具有继承与派生以及多态性的类。 要实现的主要功能如下： 1）建立书籍类、图书类型类、图书类 2）书籍、图书类型、图书信息的初始化 3）书籍、图书类型、图书信息的添加、修改、删除、查找 4）图书信息的输出 5）对图书信息按编号、书名排序 6）将图书信息保存为文件

好的，下面是一个简单的C++代码示例，实现了书籍类(Book)、图书类型类(BookType)、图书类(Library)以及对图书信息的添加、修改、删除、查找、排序和输出等功能。同时，使用了多态性和虚函数的知识。

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <string>

using namespace std;

// 基类：书籍类
class Book {
protected:
    string title;
    string author;
    string publisher;
    int year;
    int pages;
public:
    Book(string t = "", string a = "", string p = "", int y = 0, int pg = 0)
     : title(t), author(a), publisher(p), year(y), pages(pg) {}
    virtual ~Book() {}
    virtual void display() const = 0;  // 纯虚函数
    virtual void input() {
        cout << "Title: ";
        getline(cin, title);
        cout << "Author: ";
        getline(cin, author);
        cout << "Publisher: ";
        getline(cin, publisher);
        cout << "Publication Year: ";
        cin >> year;
        cout << "Number of Pages: ";
        cin >> pages;
        cin.ignore();  // 忽略换行符
    }
    string getTitle() const {
        return title;
    }
    string getAuthor() const {
        return author;
    }
    string getPublisher() const {
        return publisher;
    }
    int getYear() const {
        return year;
    }
    int getPages() const {
        return pages;
    }
};

// 派生类：图书类型类
class BookType : public Book {
private:
    string type;
public:
    BookType(string t = "", string a = "", string p = "", int y = 0, int pg = 0, string tp = "")
     : Book(t, a, p, y, pg), type(tp) {}
    void display() const {
        cout << "Title: " << title << endl;
        cout << "Author: " << author << endl;
        cout << "Publisher: " << publisher << endl;
        cout << "Publication Year: " << year << endl;
        cout << "Number of Pages: " << pages << endl;
        cout << "Type: " << type << endl << endl;
    }
    void input() {
        Book::input();
        cout << "Type: ";
        getline(cin, type);
    }
    string getType() const {
        return type;
    }
};

// 派生类：图书类
class Library : public Book {
private:
    int id;  // 图书编号
    static int count;  // 统计图书数目
public:
    Library(string t = "", string a = "", string p = "", int y = 0, int pg = 0)
     : Book(t, a, p, y, pg), id(++count) {}
    void display() const {
        cout << "ID: " << id << endl;
        cout << "Title: " << title << endl;
        cout << "Author: " << author << endl;
        cout << "Publisher: " << publisher << endl;
        cout << "Publication Year: " << year << endl;
        cout << "Number of Pages: " << pages << endl << endl;
    }
    void input() {
        Book::input();
    }
    int getID() const {
        return id;
    }
    // 按编号排序
    static bool cmpID(const Library& l1, const Library& l2) {
        return l1.id < l2.id;
    }
    // 按书名排序
    static bool cmpTitle(const Library& l1, const Library& l2) {
        return l1.title < l2.title;
    }
};

int Library::count = 0;  // 初始化静态成员变量

// 图书管理类
class BookManager {
private:
    vector<Book*> books;  // 所有图书的指针数组
public:
    ~BookManager() {
        for (int i = 0; i < books.size(); i++) {
            delete books[i];
        }
    }
    // 添加书籍
    void addBook(Book* book) {
        books.push_back(book);
    }
    // 修改书籍
    void modifyBook(int id) {
        for (int i = 0; i < books.size(); i++) {
            Library* lib = dynamic_cast<Library*>(books[i]);  // 动态类型转换
            if (lib != nullptr && lib->getID() == id) {
                lib->input();
                cout << "Book modified successfully!" << endl << endl;
                return;
            }
        }
        cout << "Book not found!" << endl << endl;
    }
    // 删除书籍
    void removeBook(int id) {
        for (int i = 0; i < books.size(); i++) {
            Library* lib = dynamic_cast<Library*>(books[i]);
            if (lib != nullptr && lib->getID() == id) {
                books.erase(books.begin() + i);
                cout << "Book removed successfully!" << endl << endl;
                return;
            }
        }
        cout << "Book not found!" << endl << endl;
    }
    // 查找书籍
    void searchBook(string keyword) {
        for (int i = 0; i < books.size(); i++) {
            Library* lib = dynamic_cast<Library*>(books[i]);
            if (lib != nullptr && (lib->getTitle().find(keyword) != string::npos || 
                                   lib->getAuthor().find(keyword) != string::npos)) {
                books[i]->display();
            }
        }
    }
    // 按编号排序
    void sortByID() {
        sort(books.begin(), books.end(), Library::cmpID);
    }
    // 按书名排序
    void sortByTitle() {
        sort(books.begin(), books.end(), Library::cmpTitle);
    }
    // 输出所有图书信息
    void displayAll() {
        for (int i = 0; i < books.size(); i++) {
            books[i]->display();
        }
    }
    // 保存图书信息到文件
    void saveToFile(string filename) {
        ofstream fout(filename);
        if (!fout) {
            cout << "Failed to open file: " << filename << endl;
            return;
        }
        for (int i = 0; i < books.size(); i++) {
            fout << books[i]->getTitle() << '\t' << books[i]->getAuthor() << '\t' 
                 << books[i]->getPublisher() << '\t' << books[i]->getYear() << '\t' 
                 << books[i]->getPages() << '\t';
            Library* lib = dynamic_cast<Library*>(books[i]);
            if (lib != nullptr) {
                fout << lib->getID();
            }
            fout << endl;
        }
        fout.close();
        cout << "Books saved to file: " << filename << endl << endl;
    }
};

int main() {
    BookManager manager;
    while (true) {
        cout << "1. Add Book" << endl;
        cout << "2. Modify Book" << endl;
        cout << "3. Remove Book" << endl;
        cout << "4. Search Book" << endl;
        cout << "5. Sort by ID" << endl;
        cout << "6. Sort by Title" << endl;
        cout << "7. Display All Books" << endl;
        cout << "8. Save to File" << endl;
        cout << "0. Exit" << endl;
        int choice;
        cin >> choice;
        cin.ignore();  // 忽略换行符
        cout << endl;
        switch (choice) {
            case 1: {
                cout << "1. Book Type" << endl;
                cout << "2. Library" << endl;
                int type;
                cin >> type;
                cin.ignore();
                if (type == 1) {
                    BookType* book = new BookType();
                    book->input();
                    manager.addBook(book);
                } else if (type == 2) {
                    Library* book = new Library();
                    book->input();
                    manager.addBook(book);
                } else {
                    cout << "Invalid choice!" << endl << endl;
                }
                break;
            }
            case 2: {
                int id;
                cout << "Enter Book ID: ";
                cin >> id;
                manager.modifyBook(id);
                break;
            }
            case 3: {
                int id;
                cout << "Enter Book ID: ";
                cin >> id;
                manager.removeBook(id);
                break;
            }
            case 4: {
                string keyword;
                cout << "Enter Keyword: ";
                getline(cin, keyword);
                manager.searchBook(keyword);
                break;
            }
            case 5: {
                manager.sortByID();
                cout << "Books sorted by ID." << endl << endl;
                break;
            }
            case 6: {
                manager.sortByTitle();
                cout << "Books sorted by Title." << endl << endl;
                break;
            }
            case 7: {
                manager.displayAll();
                break;
            }
            case 8: {
                string filename;
                cout << "Enter Filename: ";
                getline(cin, filename);
                manager.saveToFile(filename);
                break;
            }
            case 0: {
                return 0;
            }
            default: {
                cout << "Invalid choice!" << endl << endl;
                break;
            }
        }
    }
}

该程序通过使用基类和派生类，实现了对书籍信息的建立，图书类型类和图书类继承自书籍类，同时使用了多态性和虚函数的知识，其中图书类(Library)还添加了一个静态成员变量count，统计图书数目。程序实现了对图书信息的初始化、添加、修改、删除、查找、排序和输出等功能，并可以将图书信息保存到文件中。