子类继承父类

 public class ParentClass
    {
        public ParentClass()
        {
            Console.WriteLine("父类构造函数");
        }
        public void SayHello()
        {
            Console.WriteLine("我是父类");
        }
    }

    public class ChildClass:ParentClass
    {
        public ChildClass()
        {
            Console.WriteLine("子类构造函数");
        }
        public static void Main()
        {
            ChildClass child = new ChildClass();//依次调用父类构造函数和子类构造函数
            child.SayHello();
        }
    }