浅谈C#中重写和隐藏的区别

重写

派生类与基类中方法名、返回参数类型、参数个数均一致，就称派生类重写了基类中的方法。

using System;
using System.Collections.Generic;

namespace Day0
{
    class Program
    {
        static void Main(string[] args)
        {
            Transport transport = new Transport();
            Car car = new Car();
            Bicycle bicycle = new Bicycle();

            transport.Drive();
            transport.Refuel();
            Console.WriteLine("transport oil = "+transport.oil);
            Console.WriteLine("==============");
            transport = car;
            transport.Drive();
            transport.Refuel();
            Console.WriteLine("transport oil = " + transport.oil);
            car.Drive();
            car.Refuel();
            Console.WriteLine("transport oil = " + transport.oil);
            Console.WriteLine("car oil = " + car.oil);
            Console.WriteLine("==============");
            transport = bicycle;
            transport.Drive();
            transport.Refuel();
            Console.WriteLine("transport oil = " + transport.oil);
            bicycle.Drive();
            bicycle.Refuel();
            Console.WriteLine("transport oil = " + transport.oil);
            Console.WriteLine("bicyle oil = " + bicycle.oil);

        }
    }
    class Transport
    {
        public int oil = 100;
        public virtual void Drive()
        {
            Console.WriteLine("驾驶交通工具...");
            oil -= 20;
        }
        public void Refuel()
        {
            Console.WriteLine("默认加注燃料");
            oil += 20;
        }

    }
    class Car : Transport
    {
        public override void Drive()
        {
            oil -= 30;
            Console.WriteLine("驾驶小轿车...");
        }
        public new void Refuel()
        {
            oil += 30;
            Console.WriteLine("小汽车加注燃料");
        }
    }
    class Bicycle : Transport
    {
        public override void Drive()
        {
            oil -= 0;
            Console.WriteLine("骑自行车...");
        }
        public new void Refuel()
        {
            oil += 0;
            Console.WriteLine("自行车加注燃料");
        }
    }

}

　　运行结果

 可以看出重写是多态的，当我们调用Drive方法时候，子类方法是覆盖掉父类中的方法的；而对于隐藏父类方法并不会被覆盖。

归其原因，重写是子类方法表添加新的记录，运行时修改父级方法表中地址，所以transport 是因为Drive方法地址被修改了出现多态。（动态绑定）

而隐藏仅仅是在子类方法表中添加新的记录，子类型引用调用子类型方法（Refuel），父类型引用调用父类Refuel方法（静态绑定）编译时便确定。