C++ typedef的一个用法

#include <iostream>
#include <cstring>
using namespace std;
struct Books
{
    char  title[50];
    char  author[50];
    char  subject[100];
    int   book_id;
};

int main()
{
    struct Books book;

    strcpy(book.title, "C 教程");
    strcpy(book.author, "Runoob");
    strcpy(book.subject, "编程语言");
    book.book_id = 12345;

    printf("书标题 : %s\n", book.title);
    printf("书作者 : %s\n", book.author);
    printf("书类目 : %s\n", book.subject);
    printf("书 ID : %d\n", book.book_id);
    system("pause");
    return 0;
}

#include <iostream>
#include <cstring>
using namespace std;
typedef struct Books
{
    char  title[50];
    char  author[50];
    char  subject[100];
    int   book_id;
};

int main()
{
    struct Books book;

    strcpy(book.title, "C 教程");
    strcpy(book.author, "Runoob");
    strcpy(book.subject, "编程语言");
    book.book_id = 12345;

    printf("书标题 : %s\n", book.title);
    printf("书作者 : %s\n", book.author);
    printf("书类目 : %s\n", book.subject);
    printf("书 ID : %d\n", book.book_id);
    system("pause");
    return 0;
}