记录一些笔试题

class Program
    {
        static void Main(string[] args)
        {
            B b = new B();
            A a = new B();
            Console.Read();
        }
    }

    public class A
    {
        public A()
        {
            PrintFields();
        }

        public virtual void PrintFields()
        {
            
        }
    }

    public class B : A
    {
        private int x = 1;
        private int y;
        public B()
        {
            y = -1;
        }

        public override void PrintFields()
        {
            Console.WriteLine($"x={x}, y = {y}");
        }
    }