对象的思考1

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

namespace ConsoleApplication5
{
    class doubi
    {
        doubi d =new doubi();
        int flag;
        public doubi()
        {
            flag = 0;
            Console.WriteLine(d.flag);
        }
        private void put()
        {
            Console.WriteLine(d.flag);
        }
    }
    class Program
    {

        static void Main(string[] args)
        {
            doubi db = new doubi();
        }
    }
}