nstruct.c

/* ===================================== */
/* ===== n instances of structures ===== */
/* ===================================== */

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

struct Books {
    char title[50];
    char author[50];
    char subject[100];
    int book_id;
};

int main() {

    // Declare 2 instances of structure books
    struct Books book[100];
    int n,i;
    printf("Enter the number of books: ");
    scanf("%d",&n);

    // Enter the details of all books
    for(i=0;i<n;i++) {
        printf("Enter the title of book %d: ",i+1);
        scanf("%s",book[i].title);
        printf("Enter the author of book %d: ",i+1);
        scanf("%s",book[i].author);
        printf("Enter the subject of book %d: ",i+1);
        scanf("%s",book[i].subject);
        book[i].book_id = 10000+8*i;
    }

    // Print the details of both books
    for(i=0;i<n;i++) {
        printf("\nTitle of book %d: %s",i+1,book[i].title);
        printf("\nAuthor of book %d: %s",i+1,book[i].author);
        printf("\nSubject of book %d: %s",i+1,book[i].subject);
        printf("\nBook ID of book %d: %d",i+1,book[i].book_id);
    }

    return 0;
}