面向对象：继承关系

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication3
{
    class shengwu
    {
        private string _Name;

        public string Name
        {
            get { return _Name; }
            set { _Name = value; }
        }
        public void life()
        {
            Console.WriteLine("I am alive!");
        }

    }
}

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication3
{
    class dongwu:shengwu
    {
        private string _Dname;

        public string Dname
        {
            get { return _Dname; }
            set { _Dname = value; }
        }
        public void eat()
        {
            Console.WriteLine("I am hungry!");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication3
{
    class zhiwu:shengwu
    {
        private string _Zname;

        public string Zname
        {
            get { return _Zname; }
            set { _Zname = value; }
        }
        public void light()
        {
            Console.WriteLine("光合作用！");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication3
{
    class zhiwu:shengwu
    {
        private string _Zname;

        public string Zname
        {
            get { return _Zname; }
            set { _Zname = value; }
        }
        public void light()
        {
            Console.WriteLine("光合作用！");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication3
{
    class tiger:dongwu
    {
        private string type;

        public string Type
        {
            get { return type; }
            set { type = value; }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            shengwu data = new shengwu();//父类
            data.Name = "GOD";
            Console.WriteLine(data.Name);
            data.life();



            dongwu ddata = new dongwu();
            ddata.eat();//子类自身的属性：多态
            ddata.life();//子类继承父类的life（）方法
            ddata.Dname="dog";//子类继承父类的Sname



            zhiwu zdata = new zhiwu();
            zdata.Zname = "";//继承父类同上



            tiger tdata = new tiger();
            tdata.Name = "";//继承祖父类shengwu
            tdata.Dname = "";//继承父类dongwu
            tdata.Type = "";//自身属性



            object odata = data;//所有类的基类
            shengwu sdata = ddata;//子类可以直接转化为父类;ddata子类转成shengwu父类
            dongwu adata = (dongwu)ddata;//父类转子类条件：父类的对象必须是由某个子类的对象转换来的，才能转换回去：把转化成父类的ddata转换为子类ddata
            Console.WriteLine(adata.Dname);//
            //zhiwu zzdata = (zhiwu)ddata;不可以，ddata本身为dongwu类，不能强制转换为zhiwu类
            Console.ReadLine();
        }
    }
}