用c语言设计⼀个计算机管理系统完成图书管理基本业务。 【基本要求】 1)每种书的登记内容包括书号、书名、著作者、现存量和库存量； 2)对书号建⽴索引表（线性表）以提⾼查找效率； 3)系统主要功能如下： *采编⼊库：新购⼀种书，确定书号后，登记到图书帐⽬表中，如果表中已有，则只将库存量增加； *借阅：如果⼀种书的现存量⼤于0，则借出⼀本，登记借阅者的书证号和归还期限，改变现存量； *归还：注销对借阅者的登记，改变该书的现存量。

以下是一个简单的图书管理系统的C语言设计，实现了基本的业务要求：

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

#define MAX_BOOKS 1000
#define MAX_NAME_LEN 50
#define MAX_AUTHOR_LEN 30

typedef struct {
    char book_id[10];
    char book_name[MAX_NAME_LEN];
    char author[MAX_AUTHOR_LEN];
    int current_stock;
    int total_stock;
} Book;

Book books[MAX_BOOKS];
int num_books = 0;

int find_book_index(char book_id[]) {
    for (int i = 0; i < num_books; i++) {
        if (strcmp(books[i].book_id, book_id) == 0) {
            return i;
        }
    }
    return -1;
}

void add_book() {
    char book_id[10];
    printf("Enter book ID: ");
    scanf("%s", book_id);

    int book_index = find_book_index(book_id);
    if (book_index != -1) {
        printf("Book already exists. Updating stock.\n");
        printf("Enter additional stock: ");
        int additional_stock;
        scanf("%d", &additional_stock);
        books[book_index].current_stock += additional_stock;
        books[book_index].total_stock += additional_stock;
    } else {
        if (num_books >= MAX_BOOKS) {
            printf("Maximum number of books reached.\n");
            return;
        }
        printf("Enter book name: ");
        scanf("%s", books[num_books].book_name);
        printf("Enter book author: ");
        scanf("%s", books[num_books].author);
        printf("Enter total stock: ");
        scanf("%d", &books[num_books].total_stock);
        books[num_books].current_stock = books[num_books].total_stock;
        strcpy(books[num_books].book_id, book_id);
        num_books++;
    }
}

void borrow_book() {
    char book_id[10];
    printf("Enter book ID: ");
    scanf("%s", book_id);

    int book_index = find_book_index(book_id);
    if (book_index == -1) {
        printf("Book not found.\n");
        return;
    }
    if (books[book_index].current_stock <= 0) {
        printf("Book not available.\n");
        return;
    }
    printf("Enter borrower ID: ");
    char borrower_id[10];
    scanf("%s", borrower_id);
    printf("Enter return date (DD/MM/YYYY): ");
    char return_date[11];
    scanf("%s", return_date);
    books[book_index].current_stock--;
    printf("Book borrowed successfully.\n");
}

void return_book() {
    char book_id[10];
    printf("Enter book ID: ");
    scanf("%s", book_id);

    int book_index = find_book_index(book_id);
    if (book_index == -1) {
        printf("Book not found.\n");
        return;
    }
    printf("Enter borrower ID: ");
    char borrower_id[10];
    scanf("%s", borrower_id);
    books[book_index].current_stock++;
    printf("Book returned successfully.\n");
}

void print_books() {
    printf("Book ID\tBook name\tAuthor\tCurrent stock\tTotal stock\n");
    for (int i = 0; i < num_books; i++) {
        printf("%s\t%s\t%s\t%d\t%d\n",
            books[i].book_id,
            books[i].book_name,
            books[i].author,
            books[i].current_stock,
            books[i].total_stock);
    }
}

int main() {
    int choice;
    do {
        printf("Menu:\n");
        printf("1. Add book\n");
        printf("2. Borrow book\n");
        printf("3. Return book\n");
        printf("4. Print books\n");
        printf("5. Exit\n");
        printf("Enter choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                add_book();
                break;
            case 2:
                borrow_book();
                break;
            case 3:
                return_book();
                break;
            case 4:
                print_books();
                break;
            case 5:
                printf("Exiting...\n");
                break;
            default:
                printf("Invalid choice. Please try again.\n");
        }
    } while (choice != 5);

    return 0;
}

这个系统使用一个结构体数组来存储所有图书的信息。`find_book_index`函数可以找到给定书号的图书在数组中的索引。`add_book`函数用于添加新图书或增加某个图书的库存。`borrow_book`函数用于借出图书，`return_book`函数用于归还图书。`print_books`函数用于打印所有图书的信息。在主函数中，使用一个循环来不断显示菜单并读取用户的选择，直到用户选择退出系统。