C# class 的可访问性-优快云博客

本文探讨了C#中内部(internal)访问修饰符的使用及其对类继承的影响。通过具体示例说明了当基类使用internal修饰时，派生类如何正确实现及调用方法。

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

namespace myCar
{
    public class Car
    {
        public Car()
        {
        }
        internal protected int Odometer = 0;
        public virtual void MoveForward()
        {
            Console.WriteLine("Moving Forwards");
            Odometer += 2;
            Console.WriteLine("Odometer reading :{0}", Odometer);
        }
    }   // 如果Car 的修饰符是internal的话那么RacingCar的定义必须在这个程序集里面
    public class RacingCar : Car
    {
        public override void MoveForward()
        {
            Console.WriteLine("Moving Dangerously fast forwards");
            Odometer += 30;
            Console.WriteLine("Odometer in racing car:{0}", Odometer);
        }
    }
    public static class Program
    {
        public static void Main()
        {
            Car myCar = new Car();
            myCar.MoveForward();
            RacingCar myRacingCar = new RacingCar();
            myRacingCar.MoveForward();

}
}
}

编译没有问题

如果Car的修饰符是internal

编译有问题，问题处在RacingCar不可以继承Car,代码必须这样修改过可以编译

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

namespace myCar
{
    public class Car
    {
        public Car()
        {
        }
        internal protected int Odometer = 0;
        public virtual void MoveForward()
        {
            Console.WriteLine("Moving Forwards");
            Odometer += 2;
            Console.WriteLine("Odometer reading :{0}", Odometer);
        }
        public class RacingCar : Car
        {
            public override void MoveForward()
            {
                Console.WriteLine("Moving Dangerously fast forwards");
                Odometer += 30;
                Console.WriteLine("Odometer in racing car:{0}", Odometer);
            }
        }
    }
    public static class Program
    {
        public static void Main()
        {
            Car myCar = new Car();
            myCar.MoveForward();
            Car.RacingCar myRacingCar = new Car.RacingCar(); //Car.RacingCar myRacingCar = new Car.RacingCar();  是编译不成功
            myRacingCar.MoveForward();