图书馆的书对应的数据类型定义如下： struct book { char name_of_book[100]; //书名 char author[25]; //作者 }; 编写函数实现： (1)统计某一作者编写了几本书。 (2)将所有书的记录存储到文件a.txt。 然后编写相应的主函数输入若干数据，并调用这两个函数实现相应 功能。用C语言实现

以下是实现代码：

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

struct book {
    char name_of_book[100];
    char author[25];
};

// 统计某一作者编写了几本书
int count_book_by_author(struct book *books, int size, char *author) {
    int count = 0;
    for (int i = 0; i < size; i++) {
        if (strcmp(books[i].author, author) == 0) {
            count++;
        }
    }
    return count;
}

// 将所有书的记录存储到文件a.txt
void save_books_to_file(struct book *books, int size) {
    FILE *fp = fopen("a.txt", "w");
    if (fp == NULL) {
        printf("Failed to create file!\n");
        return;
    }
    for (int i = 0; i < size; i++) {
        fprintf(fp, "%s %s\n", books[i].name_of_book, books[i].author);
    }
    fclose(fp);
}

int main() {
    struct book books[100];
    int size = 0;

    // 输入书籍信息
    printf("Please enter the book information (\"exit\" to quit):\n");
    while (1) {
        printf("Book name: ");
        fgets(books[size].name_of_book, 100, stdin);
        books[size].name_of_book[strcspn(books[size].name_of_book, "\n")] = 0;
        if (strcmp(books[size].name_of_book, "exit") == 0) {
            break;
        }
        printf("Author: ");
        fgets(books[size].author, 25, stdin);
        books[size].author[strcspn(books[size].author, "\n")] = 0;
        size++;
    }

    // 统计某一作者编写了几本书
    char author[25];
    printf("Please enter the author name: ");
    fgets(author, 25, stdin);
    author[strcspn(author, "\n")] = 0;
    int count = count_book_by_author(books, size, author);
    printf("%s has written %d books.\n", author, count);

    // 将所有书的记录存储到文件a.txt
    save_books_to_file(books, size);

    return 0;
}

其中，`fgets()` 函数用于读取用户输入的字符串，`strcspn()` 函数用于去掉字符串末尾的换行符。`count_book_by_author()` 函数使用了 `strcmp()` 函数来比较作者名字是否相同，`save_books_to_file()` 函数使用了 `fprintf()` 函数来向文件中写入数据。