c++ 虚函数

class CFigure     //基类-图形类{protected:double x,y; //成员变量public:void SetDim(double i,double j=0.0) //设置图形参数{x=i;y=j;}virtual void GetShowArea() //虚函数计算显示面积{cout<<"无法计算面积\n";}};class CTriangle:public CFigure     //三角形类{public:void GetShowArea() //覆盖虚函数{cout<< " 面积："<<x*0.5*y<<endl;}};int main(){CFigure *figure;CFigure basic;CTriangle triangle;figure = &basic;figure->SetDim(8.0,5.0);figure->GetShowArea();figure = ▵figure->SetDim(10.0, 10.0);figure->GetShowArea();return 0;}//输出//无法计算面积//面积=50