第十三天打卡

以平面图形类Plane为基类公有派生三角形类Triangle，main(void)函数完成对其的测试。

题目：

#include <iostream>
#include<cmath>
using namespace std;
//点类Point
class Point{
private:
    double x;
    double y;
public:
    Point(double xv=0,double yv=0);/*构造函数*/
    Point(const Point &p);         /*拷贝构造*/
    ~Point();                      /*析构函数*/
    virtual void show()const;      /*显示*/
    void setX(double xv);          /*设置X坐标*/
    void setY(double yv);          /*设置Y坐标*/
    double getX() const;           /*获取X坐标*/
    double getY() const;           /*获取Y坐标*/
};
Point::Point(const double xv,const double yv){/*构造函数*/
    x=xv;
    y=yv;
    cout<<"Point Constructor run"<<endl;
}
Point::Point(const Point &p){/*拷贝构造*/
    x=p.x;
    y=p.y;
    cout<<"Point CopyConstructor run"<<endl;
}
Point::~Point(){/*析构函数*/
    cout<<"Point Destructor run"<<endl;
}
void Point::show() const{/*显示*/
    cout<<"Point(X="<<x<<",Y="<<y<<")";
}
void Point::setX(double xv){/*设置X坐标*/
    x=xv;
}
void Point::setY(double yv){/*设置Y坐标*/
    y=yv;
}
double Point::getX() const{/*获取X坐标*/
    return x;
}
double Point::getY() const{/*获取Y坐标*/
    return y;
}
class Plane{/*平面图形基类*/
public:
    virtual double length()const=0;/*周长*/
    virtual double area()const=0;  /*面积*/
};

/*请在这里填写答案*/

void length(Plane *p){/*平面图形的周长函数*/
    cout<<"Length="<<p->length()<<endl;
}
void area(Plane &p){/*平面图形的面积函数*/
    cout<<"Area="<<p.area()<<endl;
}
//主函数
int main(void){
    double x,y;
    Point p1,p2(1,1),p3(2,2);
    Triangle t1,t2(t1);
    t1.show();
    cout<<endl;
    area(t1);
    length(&t1);
    cin>>x>>y;
    p1.setX(x);
    p1.setY(y);
    t2.setA(p1);
    t2.setB(p2);
    t2.setC(p3);
    t2.show();
    cout<<endl;
    area(t2);
    length(&t2);
    return 0;
}

答案：

double pointDis(const Point &p1,const Point &p2)
{
    return sqrt(pow(p1.getX() - p2.getX(),2) + pow(p1.getY() - p2.getY(), 2));
}
class Triangle : public Plane
{
private:
    Point a, b, c;
public:
    Triangle(const Point &o = Point(0,0), const Point &p = Point(0,0), const Point &q = Point(0,0)) : a(o), b(p), c(q)
    {
        cout << "Triangle Constructor run" << endl;
    }
    Triangle(const Triangle &t) : a(t.a), b(t.b), c(t.c)
    {
        cout << "Triangle CopyConstructor run" << endl;
    }
    ~Triangle()
    {
        cout << "Triangle Destructor run" << endl;
    }
    void setA(const Point &t)
    {
        this->a = t;
    }
    Point getA() const
    {
        return a;
    }
    void setB(const Point &t)
    {
        this->b = t;
    }
    Point getB() const
    {
        return b;
    }
    void setC(const Point &t)
    {
        this->c = t;
    }
    Point getC() const
    {
        return c;
    }
    void show() const
    {
        cout<<"Triangle(A=";
        a.show();
        cout<<",B=";
        b.show();
        cout<<",C=";
        c.show();
        cout<<")";
    }

    double length() const
    {
        return pointDis(a,b) + pointDis(a,c) + pointDis(b,c);
    }
    double area() const
    {
        double p = length() / 2;
        return sqrt(p * (p - pointDis(a,b)) *
                    (p - pointDis(a,c)) *
                    (p - pointDis(b,c)));
    }

};