父类和子类的构造函数

 public abstract class A
    {
        public A()
        {
            Console.WriteLine('A');
        }
        public virtual void Fun()
        {
            Console.WriteLine("A.Fun()");
        }
    }

    public class B : A
    {
        public B()
        {
            Console.WriteLine('B');
        }
        public new void Fun()    
        {
            Console.WriteLine("B.Fun()");
        }
    }

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

class A
    {
        internal int number;
        public A(int n)
        {
            number = n;
            Console.WriteLine("A的构造函数");
        }
    }

    class B : A
    {
        public B(int n)
            : base(n)
        {
            Console.WriteLine("B的构造函数");
        }
    }

    class Program
    {
        static void Main(string[] args)
        {

            A a = new B(3);
            Console.WriteLine(a.number);
            Console.ReadKey();
        }
    }