/*写一个程序，定义抽象类型Shape，由他派生五个类：Circle(圆形),Square(正方形),
Rectangle(矩形),Trapezoid(梯形),Triange(三角形)。用虚函数分别计算几种图形的面积，
并求他们的和。要求用基类指针数组，使它的每一个元素指向一个派生类的对象。
*/
#define pi 3.1415926
class Shape
{
public:
virtual void getArea()=0;
};
class Circle:public Shape
{
public:
Circle(double r=0.0)
:r(r)
{}
void getArea()
{
cout<<pi*r*r<<endl;
}
private:
double r;
};
class Rectangle:public Shape
{
public:
Rectangle(double length,double heigh)
:length(length),heigh(heigh)
{

}
void getArea()
{
cout<<length*heigh<<endl;
}
private:
double length;
double heigh;
};
class Square:public Shape
{
public:
Square(double l=0.0)
:length(l)
{}
void getArea()
{
cout<<length*length<<endl;
}
private:
double length;
};
class Trapezoid:public Shape
{
public:
Trapezoid(double l=0.0,double m_l=0.0,double h=0.0)
:length(l),m_length(m_l),heigh(h)
{}
void getArea()
{
cout<<(length+m_length)*heigh*0.5<<endl;
}
private:
double length;
double m_length;
double heigh;

};
class Triange:public Shape
{
public:
Triange(double a=0.0,double b=0.0,double c=0.0)
:l_a(a),l_b(b),l_c(c)
{}
void getArea()
{
double s=0.5*(l_a+l_b+l_c);
cout<<sqrt(s*(s-l_a)*(s-l_b)*(s-l_c))<<endl;
}
private:
double l_a;
double l_b;
double l_c;
};

void fun(Shape* ps)
{
ps->getArea();
}

int main()
{
/*Circle c(2);
fun(&c);
Rectangle r(2.0,3);
fun(&r);
Square s(4.0);
fun(&s);
Trapezoid Tt(3.0,5,3);
fun(&Tt);
Triange t(5,12,13.0);
fun(&t);
*/
//Shape* ps[5]={&c,&r,&s,&Tt,&t};


               // 这样写到底对不对，为什么VS2010debug 运行过的去 而release运行会崩溃
Shape* ps[5]={&Circle(4),&Rectangle(2.3,3),&Square(3.0),&Trapezoid(2,4,4),&Triange(3,4,5)};
for(int i=0;i<5;i++)
{
                              fun(ps[i]);
}