// 定义一个抽象的父类
abstract class Figure
{
//声明抽象方法：
//父类中的所有家里人可以用的方法必须都应用到子类中
abstract public object getValue();//或者用virtual但是后面必须声明主体部分{ return null; }
abstract public Figure Add(Figure f1); //{ return null; }
abstract public Figure Sub(Figure f1);
abstract public Figure Mul(Figure f1);
abstract public Figure Div(Figure f1);
}
// 实数子类
class DoubleFigure : Figure
{
//声明一个double型字段来存放数据
protected double _myDouble;
//运行的时候调用实现初始化
public DoubleFigure(double num1)
{
this._myDouble = num1;
}
// 重写父类中输出结果的方法
public override object getValue()
{
return _myDouble;
}
//实数相加
public override Figure Add(Figure f1)
{
double doublenum = (double)this.getValue() + (double)f1.getValue();
//f1.getValue()实际执行的结果类型不由f1声明时的类型决定，而是由指向堆中的内容决定
DoubleFigure df = new DoubleFigure(doublenum);
return df;//这里返回值类型为什么不是Figure也可以
//在堆中开辟的空间地址传给了父类中的变量------父类的变量指向子类中的实例
//父类变量能传递给子类中变量是因为实际类型没有改变
}
//这里不能用运算符的重载：operator必须和public static一同使用，而override不能与static同用
//public override Figure operator +(DoubleFigure f1)
//{
// double doubleNum = (double)this.getValue() + (double)f1.getValue();
// DoubleFigure df = new DoubleFigure(doubleNum);
// return df;
//}
// 实数相减
public override Figure Sub(Figure f1)
{
double doubleNum = (double)this.getValue() - (double)f1.getValue();
DoubleFigure df = new DoubleFigure(doubleNum);
return df;
}
// 实数相乘
public override Figure Mul(Figure f1)
{
double doubleNum = (double)this.getValue() * (double)f1.getValue();
DoubleFigure df = new DoubleFigure(doubleNum);
return df;
}
//实数相除
public override Figure Div(Figure f1)
{
if ((double)f1.getValue()!=0)
{
double doubleNum = (double)this.getValue() / (double)f1.getValue();
DoubleFigure df = new DoubleFigure(doubleNum);
return df;
}
else
{
Console.WriteLine("除数不能为0！");
return new DoubleFigure(0);
}
}
//隐式转换方法实现DoubleFigure类型的数隐式转换为int型
public static implicit operator DoubleFigure(int myInt1)
{
return new DoubleFigure(myInt1);
}
static void Main(string[] args)
{
//父类的变量指向子类的实例
Figure f1 = new DoubleFigure(6);//整数实例
Figure f2 = new DoubleFigure(1.2); //实数实例
DoubleFigure f3 = (DoubleFigure)f1.Div(f2);
Console.WriteLine(f3.getValue());
Console.ReadKey();
}