看不懂这个书上的例子,在线等待高手进来看一下,从来没有见过这样迷茫的例子.
using   System;
public   abstract   class   Shape
{
private   string   myId;
public   Shape(string   s)
{
Id=s;
}
public   string   Id
{
get
{
return   myId;
}
set
{
myId=value;
}
}
public   abstract   double   Area
{
get;
}
public   virtual   void   Draw()
{
Console.WriteLine( "Draw   Shape   Icon ");
}
public   override   string   ToString()
{
return   Id   +   "   Area=   "   +   string.Format( "{0:F2} ",Area);
}
}
//正方形类
public   class   Square:Shape
{
private   int   mySide;
public   Square(int   side,string   id):base(id)
{
mySide=side;
}
public   override   double   Area
{
get
{
return   mySide   *   mySide;
}
}
public   override   void   Draw()
{
Console.WriteLine( "Draw   4   Siede:   "   +   mySide);
}
}
//测试
public   class   TestClass
{
public   static   void   Main(string[]args)
{
              Square   x=new   Square(5, "Square   #1 ");
      Console.WriteLine(x);//不明白为什么能输出: "Square   #1   Area=   25.00 "程序当中并没有调用其它的方法啊?
}
}


------解决方案--------------------
Console.WriteLine(x);//对于object类型的，就会调用ToString的，你的基类里定义了ToString，就会被调用。这句相当于：
Console.WriteLine(x.ToString());