继承

继承基础

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



namespace cSharpTest
{
    class Fxx
    {
        static void Main(string[] args)
        {


        }

    }

    public class Student
    {
        public Student(string name, int age)
        {
            this.Name = name;
            this.Age = age;
        }
        string _name;
        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }

        int _age;
        public int Age
        {
            get { return _age; }
            set { _age = value; }
        }
        private static int _id;

        //静态只能调用静态！
        public static void SayId()
        {
            Console.WriteLine(_id);
        }

        public void SayHello()
        {
            Console.WriteLine("My name is {0}, my age is {1}", this.Name, this.Age);

        }

    }


    public class Pupil:Student
    {

        //必须这么写 不然报错！
        public Pupil(string name, int age, int id): base(name, age)
        {
            //this.Name = name;
            //this.Age = age;
            //this.Gender = gender;
            this.Id = id;
        }

        private int _id;
        public int Id
        {
            get { return _id; }
            set { _id = value; }

        }

        public void SayPupil()
        {
            Console.WriteLine("I am a pupil.");
        }

    }

}

里氏转换

1.子类可以复制给父类，如果有一个地方需要父类作为参数，可以给父类赋值给父类

Person p1= new Student();

2.如果父类中装的是子类对象，那么可以将父类强转为子类对象

Student s1 =(Student)p1;

3.转换之前需要判断
is 转换成功ture,失败false
as 能转换则返回对应对象，否则返回None

if(p is Teacher)
{
}
else{

}

as用法

Teacher t = p as Teacher();

练习

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

namespace CsharpTest0621
{

    class Fxx
    {
        static void Main(string[] args)
        {
            //创建10个对象，循环调用他们的方法
            //Student s = new Student();太麻烦
            Person[] personList = new Person[10];
            Random r = new Random();//随机数对象
            for (int i = 0; i < personList.Length; i++)
            {
                int rNumber = r.Next(1, 6);
                switch (rNumber)
                {
                    case 1: personList[i] = new Student();
                        break;
                    case 2: personList[i] = new Teacher();
                        break;
                    case 3:
                        personList[i] = new Worker();
                        break;
                    case 4:
                        personList[i] = new Piger();
                        break;
                    case 5:
                        personList[i] = new Gay();
                        break;
           
                }


            }

            for (int i = 0; i < personList.Length; i++)
            {
                if (personList[i] is Student)
                {
                    ((Student)personList[i]).StudenSay();
                }
                else if (personList[i] is Teacher)
                {
                    ((Teacher)personList[i]).TeacherSay();
                }
                else if (personList[i] is Worker)
                {
                    ((Worker)personList[i]).WorkerSay();
                }
            }

        }

        public class Person
        {
            public void PersonSay()
            {
                Console.WriteLine("I am a person.");

            }

        }

        public class Student:Person
        {
            public void StudenSay()
            {
                Console.WriteLine("I am a student.");
            }
        }

        public class Teacher:Person
        {
            public void TeacherSay()
            {
                Console.WriteLine("I am a teacher.");

            }
        }
       
        public class Worker : Person
        {
            public void WorkerSay()
            {
                Console.WriteLine("I am a Worker.");
            }
        }

        public class Piger : Person
        {
            public void PigerSay()
            {
                Console.WriteLine("I am a Piger.");
            }
        }

        public class Gay : Person
        {
            public void GaySay()
            {
                Console.WriteLine("I am a Gay.");
            }
        }

    }

}

protected

protected 可以让当前类的内部 已经该类的子类里面