多态

using System;

namespace ConsoleApplication2
{
 /// <summary>
 /// Class1 的摘要说明。
 /// </summary>
 class Class1
 {
  /// <summary>
  /// 应用程序的主入口点。
  /// </summary>
  [STAThread]
  static void Main(string[] args)
  {
   //
   // TODO: 在此处添加代码以启动应用程序
   //
   vehicle myvc=new vehicle();
   car mycar=new car(4,2,5);
   truck mytk=new truck(6,5,3,10);
   myvc.speeking();
   myvc=mycar;
   myvc.speeking();
   mycar.speeking();
   myvc=mytk;
   myvc.speeking();
   mytk.speeking();
   Console.ReadLine();
  }
 }

 //class vehicle
 class vehicle
 {
  public int wheels;
  protected float weight;
  public vehicle()
  {
  }
  public vehicle(int w,float g)
  {
           this.wheels=w;
     this.weight=g;
  }
  public virtual void speeking()
  {
   Console.WriteLine("the vehicle is speeking!"+this.wheels+this.weight);
  }

 }

 //class car
 class car:vehicle
 {
  private int passengers;
  public car(int w,float g,int p):base(w,g)
  {
   wheels=w;
   weight=g;
   this.passengers=p;
  }
  public override void speeking()
  {
   Console.WriteLine("the car speeking!"+this.wheels+this.weight+this.passengers);
  }
 }

 //class

 class truck:vehicle
 {
  int passengers;
  float load;
  public truck(int w,float g,int p,float l):base(w,g)
  {
   this.wheels=w;
   this.weight=g;
   this.passengers=p;
   this.load=l;
  }
  public override void speeking()
  {
   Console.WriteLine("the truck speeking!"+this.wheels+this.weight+this.passengers+this.load);
  }

 }
}
编译时多态：通过重载来实现的，虚类vechile通过子类的继承实现多态，子类再付给Base类就可以实现多态的效果了。