用C语言写一段图书馆系统

好的，以下是一个简单的图书馆系统的C语言代码示例：

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

#define MAX_BOOKS 1000

typedef struct {
    char title[100];
    char author[100];
    int year_published;
    int num_copies;
    int num_copies_available;
} Book;

Book books[MAX_BOOKS];
int num_books = 0;

void add_book() {
    Book book;
    printf("Enter book title: ");
    fgets(book.title, sizeof(book.title), stdin);
    book.title[strlen(book.title) - 1] = '\0';
    printf("Enter book author: ");
    fgets(book.author, sizeof(book.author), stdin);
    book.author[strlen(book.author) - 1] = '\0';
    printf("Enter year published: ");
    scanf("%d", &book.year_published);
    printf("Enter number of copies: ");
    scanf("%d", &book.num_copies);
    book.num_copies_available = book.num_copies;
    books[num_books++] = book;
    printf("Book added successfully!\n");
}

void display_books() {
    printf("%-30s%-30s%-20s%-20s%s\n", "Title", "Author", "Year Published", "Num Copies", "Num Copies Available");
    for (int i = 0; i < num_books; i++) {
        Book book = books[i];
        printf("%-30s%-30s%-20d%-20d%d\n", book.title, book.author, book.year_published, book.num_copies, book.num_copies_available);
    }
}

void borrow_book() {
    char title[100];
    printf("Enter book title: ");
    fgets(title, sizeof(title), stdin);
    title[strlen(title) - 1] = '\0';
    for (int i = 0; i < num_books; i++) {
        Book *book = &books[i];
        if (strcmp(book->title, title) == 0) {
            if (book->num_copies_available > 0) {
                book->num_copies_available--;
                printf("Book borrowed successfully!\n");
                return;
            } else {
                printf("No copies of the book are available!\n");
                return;
            }
        }
    }
    printf("Book not found!\n");
}

void return_book() {
    char title[100];
    printf("Enter book title: ");
    fgets(title, sizeof(title), stdin);
    title[strlen(title) - 1] = '\0';
    for (int i = 0; i < num_books; i++) {
        Book *book = &books[i];
        if (strcmp(book->title, title) == 0) {
            if (book->num_copies_available < book->num_copies) {
                book->num_copies_available++;
                printf("Book returned successfully!\n");
                return;
            } else {
                printf("Invalid return!\n");
                return;
            }
        }
    }
    printf("Book not found!\n");
}

int main() {
    while (1) {
        printf("1. Add book\n");
        printf("2. Display books\n");
        printf("3. Borrow book\n");
        printf("4. Return book\n");
        printf("5. Exit\n");
        int choice;
        printf("Enter your choice: ");
        scanf("%d", &choice);
        getchar();
        switch (choice) {
            case 1:
                add_book();
                break;
            case 2:
                display_books();
                break;
            case 3:
                borrow_book();
                break;
            case 4:
                return_book();
                break;
            case 5:
                exit(0);
            default:
                printf("Invalid choice!\n");
        }
    }
    return 0;
}

这段程序实现了一个简单的图书馆系统，包括添加书籍、显示书籍、借阅书籍和归还书籍等功能。用户可以通过在菜单中选择不同的选项来执行不同的功能。