图书管理系统设计与实现单链表

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首先，单链表是一种常见的数据结构，用于存储一系列的数据元素。在图书管理系统中，我们可以使用单链表来存储图书信息。

单链表由多个节点组成，每个节点包含一个数据元素和一个指向下一个节点的指针。在图书管理系统中，每个节点可以存储一本书的信息，例如书名、作者、出版社、ISBN号等等。

我们可以使用一个头指针来指向链表的第一个节点。通过遍历链表，我们可以实现对图书信息的增、删、改、查等操作。

下面是一个简单的示例代码，用于实现单链表存储图书信息：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct Book {
    char title[50];
    char author[50];
    char publisher[50];
    char isbn[20];
    struct Book *next;
};

struct Book *head = NULL;

void add_book() {
    struct Book *new_book = malloc(sizeof(struct Book));
    printf("Please enter the book title: ");
    scanf("%s", new_book->title);
    printf("Please enter the book author: ");
    scanf("%s", new_book->author);
    printf("Please enter the book publisher: ");
    scanf("%s", new_book->publisher);
    printf("Please enter the book ISBN: ");
    scanf("%s", new_book->isbn);
    new_book->next = NULL;
    if (head == NULL) {
        head = new_book;
    } else {
        struct Book *current = head;
        while (current->next != NULL) {
            current = current->next;
        }
        current->next = new_book;
    }
    printf("Book added successfully!\n");
}

void list_books() {
    if (head == NULL) {
        printf("No books in the library!\n");
        return;
    }
    printf("%-50s %-50s %-50s %-20s\n", "Title", "Author", "Publisher", "ISBN");
    struct Book *current = head;
    while (current != NULL) {
        printf("%-50s %-50s %-50s %-20s\n", current->title, current->author, current->publisher, current->isbn);
        current = current->next;
    }
}

void search_book() {
    char isbn[20];
    printf("Please enter the ISBN of the book you want to search: ");
    scanf("%s", isbn);
    struct Book *current = head;
    while (current != NULL) {
        if (strcmp(current->isbn, isbn) == 0) {
            printf("%-50s %-50s %-50s %-20s\n", "Title", "Author", "Publisher", "ISBN");
            printf("%-50s %-50s %-50s %-20s\n", current->title, current->author, current->publisher, current->isbn);
            return;
        }
        current = current->next;
    }
    printf("Book with ISBN %s not found!\n", isbn);
}

void delete_book() {
    char isbn[20];
    printf("Please enter the ISBN of the book you want to delete: ");
    scanf("%s", isbn);
    if (head == NULL) {
        printf("No books in the library!\n");
        return;
    }
    if (strcmp(head->isbn, isbn) == 0) {
        struct Book *temp = head;
        head = head->next;
        free(temp);
        printf("Book deleted successfully!\n");
        return;
    }
    struct Book *current = head;
    while (current->next != NULL) {
        if (strcmp(current->next->isbn, isbn) == 0) {
            struct Book *temp = current->next;
            current->next = current->next->next;
            free(temp);
            printf("Book deleted successfully!\n");
            return;
        }
        current = current->next;
    }
    printf("Book with ISBN %s not found!\n", isbn);
}

void update_book() {
    char isbn[20];
    printf("Please enter the ISBN of the book you want to update: ");
    scanf("%s", isbn);
    struct Book *current = head;
    while (current != NULL) {
        if (strcmp(current->isbn, isbn) == 0) {
            printf("Please enter the new book title: ");
            scanf("%s", current->title);
            printf("Please enter the new book author: ");
            scanf("%s", current->author);
            printf("Please enter the new book publisher: ");
            scanf("%s", current->publisher);
            printf("Please enter the new book ISBN: ");
            scanf("%s", current->isbn);
            printf("Book updated successfully!\n");
            return;
        }
        current = current->next;
    }
    printf("Book with ISBN %s not found!\n", isbn);
}

int main() {
    int option;
    do {
        printf("Please select an option:\n");
        printf("1. Add a book to the library\n");
        printf("2. List all books in the library\n");
        printf("3. Search for a book by ISBN\n");
        printf("4. Delete a book from the library\n");
        printf("5. Update a book in the library\n");
        printf("6. Exit\n");
        printf("Your selection: ");
        scanf("%d", &option);
        switch (option) {
            case 1:
                add_book();
                break;
            case 2:
                list_books();
                break;
            case 3:
                search_book();
                break;
            case 4:
                delete_book();
                break;
            case 5:
                update_book();
                break;
            case 6:
                printf("Goodbye!\n");
                break;
            default:
                printf("Invalid option!\n");
                break;
        }
    } while (option != 6);
    return 0;
}

在这个示例代码中，我们定义了一个Book结构体，包含了书的各个信息和指向下一个节点的指针。我们还定义了一个头指针head，用于指向链表的第一个节点。

我们通过add_book()函数实现了向链表中添加图书的功能，通过list_books()函数实现了列出所有图书的功能，通过search_book()函数实现了通过ISBN号搜索图书的功能，通过delete_book()函数实现了删除指定图书的功能，通过update_book()函数实现了更新指定图书信息的功能。

在main()函数中，我们通过一个循环来实现了用户与程序的交互，让用户能够选择相应的操作。