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

namespace ConsoleApplication1
{
 
    class father
    {
        public string name="delphi";

        public father(int age)
        {
            Console.WriteLine("the father 's age is:{0}",age);
        }
        public father()
        { }
        public void print()
        {
            Console.WriteLine("the father class delphi.");
        }

        virtual public void goodfather()
        {
            Console.WriteLine("this is virtual father!!!!!!!!");

        }

    }
    class son:father
    {
        new public string name = "web";
        public son(int age):base(age)
        {

        }//important
        public son(int age,char sex,string hobby)
        {
            Console.WriteLine("age sex hobby ----3:{0},:{1},:{2}.",age,sex,hobby);
        }
        public son(int age,char sex):this(age,sex,"basketball")
        {
            Console.WriteLine("the son's age is{0},and sex is {1}:", age, sex);
        }

        public son()
        {
        }

        public void print()
        {
            Console.WriteLine("{0}",base.name);
        }
        public override void goodfather()
        {
            Console.WriteLine("this is child class 's goodfather.");
        }

    }
    class Program
    {


       
        static void Main(string[] args)
        {
            son s = new son(18);
            father f = new father(20);
            son s2 = new son(18, '1', "pool");
            son s3 = new son(12);
            son s4 = new son(12, 'd');

            //father f2 = (father)s;

            /*Console.WriteLine("{0}:", s.name);
            s.print();
            f2.print();
            Console.WriteLine("{0}:", f2.name);
            f.goodfather();
            f2.goodfather();*/

        }
    }
}