what is stucture in c code example

Example 1: structs in c

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

struct book{ //this is like making a datatype of type book
    //these are the fields
  	char name[50];
    char author[50];
    char ISBN[11];
};

int main(){
    struct book book1; //making an instance of book called book1
    /*
    normally to store integers in a struct we can do something like
    book1.number_of_pages = 22; which is correct
    however with character arrays we need to use the strcpy
    function
    */

    strcpy(book1.name, "james and the giant tatti");
    strcpy(book1.author, "Krishan Grewal");
    strcpy(book1.ISBN, "12345678987");

    printf("book name: %s\n", book1.name);
  	printf("book author: %s\n", book1.author);
  	printf("book ISBN: %s\n", book1.ISBN);

return 0;
}

Example 2: declare structure in c

struct num{
 int a ;
 int b;
};

int main()
{
    struct num n;
    //accessing the elements inside struct
    n.a=10;
    n.b=20;
}