Example of C# Structure.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CSharpStruct
{
    struct Books
    {
        public string title;
        public string author;
        public string subject;
        public int id;
    }
    class Program
    {
        static void Main(string[] args)
        {
            Books b1, b2;

            b1.title = "Little Inspiration";
            b1.author = "Mahi";
            b1.subject = "Quotes";
            b1.id = 5;

            Console.WriteLine("Book 1 title : {0}", b1.title);
            Console.WriteLine("Book 1 author : {0}", b1.author);
            Console.WriteLine("Book 1 subject : {0}", b1.subject);
            Console.WriteLine("Book 1 book_id :{0}", b1.id);

            Console.WriteLine();

            b2.title = "Suvichar";
            b2.author = "Jignesh Trivedi";
            b2.subject = "Quotes";
            b2.id = 10;

            Console.WriteLine("Book 2 title : {0}", b2.title);
            Console.WriteLine("Book 2 author : {0}", b2.author);
            Console.WriteLine("Book 2 subject : {0}", b2.subject);
            Console.WriteLine("Book 2 book_id : {0}", b2.id);

            Console.ReadLine();
        }
    }
}

Output: