用链表和文件编写一个图书管理系统

好的，下面是一个简单的图书管理系统的实现，采用链表和文件存储数据。这个系统支持添加、删除、查询和显示所有图书信息的功能。

1.定义图书结构体和链表节点结构体

#define MAX_TITLE_LENGTH 50
#define MAX_AUTHOR_LENGTH 20
#define MAX_ISBN_LENGTH 15

struct Book {
    char title[MAX_TITLE_LENGTH];
    char author[MAX_AUTHOR_LENGTH];
    char isbn[MAX_ISBN_LENGTH];
    int year;
    int quantity;
};

struct ListNode {
    struct Book book;
    struct ListNode* next;
};

2.实现链表的添加、删除和查询操作

// 添加图书
void add_book(struct ListNode** head_ref, struct Book book) {
    struct ListNode* new_node = (struct ListNode*)malloc(sizeof(struct ListNode));
    new_node->book = book;
    new_node->next = NULL;

    if (*head_ref == NULL) {
        *head_ref = new_node;
    } else {
        struct ListNode* last_node = *head_ref;
        while (last_node->next != NULL) {
            last_node = last_node->next;
        }
        last_node->next = new_node;
    }
}

// 删除图书
void delete_book(struct ListNode** head_ref, char* isbn) {
    struct ListNode* temp = *head_ref, *prev;

    if (temp != NULL && strcmp(temp->book.isbn, isbn) == 0) {
        *head_ref = temp->next;
        free(temp);
        return;
    }

    while (temp != NULL && strcmp(temp->book.isbn, isbn) != 0) {
        prev = temp;
        temp = temp->next;
    }

    if (temp == NULL) {
        return;
    }

    prev->next = temp->next;
    free(temp);
}

// 查询图书
struct Book* find_book(struct ListNode* head, char* isbn) {
    struct ListNode* temp = head;

    while (temp != NULL) {
        if (strcmp(temp->book.isbn, isbn) == 0) {
            return &(temp->book);
        }
        temp = temp->next;
    }

    return NULL;
}

3.实现文件读写操作

// 从文件中读取图书信息
void read_books(struct ListNode** head_ref, char* filename) {
    FILE* fp = fopen(filename, "r");
    if (fp == NULL) {
        printf("Error: cannot open file %s\n", filename);
        return;
    }

    char title[MAX_TITLE_LENGTH];
    char author[MAX_AUTHOR_LENGTH];
    char isbn[MAX_ISBN_LENGTH];
    int year;
    int quantity;

    while (fscanf(fp, "%s %s %s %d %d", title, author, isbn, &year, &quantity) != EOF) {
        struct Book book = { .year = year, .quantity = quantity };
        strcpy(book.title, title);
        strcpy(book.author, author);
        strcpy(book.isbn, isbn);
        add_book(head_ref, book);
    }

    fclose(fp);
}

// 将图书信息保存到文件中
void write_books(struct ListNode* head, char* filename) {
    FILE* fp = fopen(filename, "w");
    if (fp == NULL) {
        printf("Error: cannot open file %s\n", filename);
        return;
    }

    struct ListNode* temp = head;
    while (temp != NULL) {
        fprintf(fp, "%s %s %s %d %d\n", temp->book.title, temp->book.author, temp->book.isbn, temp->book.year, temp->book.quantity);
        temp = temp->next;
    }

    fclose(fp);
}

4.实现主函数，提供用户交互界面

int main() {
    struct ListNode* head = NULL;
    read_books(&head, "books.txt");

    int choice;
    do {
        printf("1. Add book\n");
        printf("2. Delete book\n");
        printf("3. Find book\n");
        printf("4. Show all books\n");
        printf("5. Quit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1: {
                struct Book book;
                printf("Enter book title: ");
                scanf("%s", book.title);
                printf("Enter book author: ");
                scanf("%s", book.author);
                printf("Enter book ISBN: ");
                scanf("%s", book.isbn);
                printf("Enter publication year: ");
                scanf("%d", &book.year);
                printf("Enter quantity: ");
                scanf("%d", &book.quantity);

                add_book(&head, book);
                printf("Book added successfully!\n");
                break;
            }

            case 2: {
                char isbn[MAX_ISBN_LENGTH];
                printf("Enter book ISBN: ");
                scanf("%s", isbn);

                delete_book(&head, isbn);
                printf("Book deleted successfully!\n");
                break;
            }

            case 3: {
                char isbn[MAX_ISBN_LENGTH];
                printf("Enter book ISBN: ");
                scanf("%s", isbn);

                struct Book* book = find_book(head, isbn);
                if (book == NULL) {
                    printf("Book not found!\n");
                } else {
                    printf("Title: %s\n", book->title);
                    printf("Author: %s\n", book->author);
                    printf("ISBN: %s\n", book->isbn);
                    printf("Year: %d\n", book->year);
                    printf("Quantity: %d\n", book->quantity);
                }
                break;
            }

            case 4: {
                struct ListNode* temp = head;
                while (temp != NULL) {
                    printf("Title: %s\n", temp->book.title);
                    printf("Author: %s\n", temp->book.author);
                    printf("ISBN: %s\n", temp->book.isbn);
                    printf("Year: %d\n", temp->book.year);
                    printf("Quantity: %d\n", temp->book.quantity);
                    printf("\n");
                    temp = temp->next;
                }
                break;
            }

            case 5: {
                printf("Saving books to file...\n");
                write_books(head, "books.txt");
                printf("Goodbye!\n");
                break;
            }

            default: {
                printf("Invalid choice!\n");
                break;
            }
        }
    } while (choice != 5);

    return 0;
}

这就是一个简单的图书管理系统的实现。当用户选择退出程序时，所有图书信息会被保存到文件中。如果下次用户再次启动程序，之前保存的图书信息会被加载到链表中。