class Program
    {
        static void Main(string[] args)
        {
            var numbd1 = GetNumBuilder();
            var numbd2 = GetNumBuilder();

            Console.WriteLine("--------数字构造器1号---------");
            for (int i = 0; i < 10; i++)
            {
                Console.WriteLine(numbd1());
            }

            Console.WriteLine("--------数字构造器2号---------");
            for (int i = 0; i < 10; i++)
            {
                Console.WriteLine(numbd2());
            }
        }

        public static Func<int> GetNumBuilder()
        {
            int i = 0;
            Func<int> f = () =>
                {
                    return i++;
                };
            return f;
        }
    }