C++

定义抽象基类Shape，由它派生出五个派生类：Circle（圆形）、Square（正方形）、Rectangle（ 长方形）、Trapezoid （梯形）和Triangle （三角形），用虚函数分别计算各种图形的面积，并求出它们的和。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。

#include <iostream>
using namespace std;

class Shape
{
public:
Shape()
{}
Shape(double s[])
{}
virtual double Area()=0;

};
class Circle:public Shape
{
public:
Circle(double r)
{
this->r=r;
}
double Area()
{
return r*r*3.1415926;
}
private:
double r;
};

class Square:public Shape
{
public:
Square(double a)
{
this->a=a;
}
double Area()
{
return a*a;
}
private:
double a;
};

class Rectangle:public Shape
{
public:
Rectangle(double x,double y)
{
this->x=x;
this->y=y;
}
double Area()
{
return x*y;
}
private:
double x;
double y;
};

class Trapezoid:public Shape
{
public:
Trapezoid(double w,double m,double h)
{
this->w=w;
this->m=m;
this->h=h;
}
double Area()
{
return ((w+m)*h)/2;
}
private:
double w;
double m;
double h;
};

class Triangle:public Shape
{
public:
Triangle(double l,double z)
{
this->l=l;
this->z=z;
}
double Area()
{
return l*z/2;
}
private:
double l;
double z;
};

int main()
{
Shape* shape[5];
double r,a,x,y,w,m,h,l,z;
cin>>r>>a>>x>>y>>w>>m>>h>>l>>z;
shape[0]=new Circle(r);
shape[1]=new Square(a);
shape[2]=new Rectangle(x,y);
shape[3]=new Trapezoid(w,m,h);
shape[4]=new Triangle(l,z);
cout<<"total of all areas = "<<shape[0]->Area()+shape[1]->Area()+shape[2]->Area()+shape[3]->Area()+shape[4]->Area();
return 0;
}