思路

![graphic.png][1]

1.1 调用路径

• 在graphic中提供calculate（）以及get（double &arg1,double & arg2）两个纯虚函数，这两个函数在其派生类graphic2D和graphic3D中实现，具体实现如下：

```c++ void graphic2D::calculate() { cal_area(); cal_perimeter(); }

void graphic2D::get(double &arg1, double &arg2) { arg1=get_area(); arg2=get_perimeter(); } void graphic3D::calculate() { cal_area(); cal_volume(); }

void graphic3D::get(double &arg1, double &arg2) { arg1=get_area(); arg2=get_volume(); }

* 以graphic2D为例，其中的calculate（）中调用了cal_area（）和cal_perimeter（），而这两个函数又是graphic2D中的纯虚函数。

## graphic.h

```c++
#ifndef GRAPHIC_H
#define GRAPHIC_H
#define PI 3.1415926
#include <math.h>

class graphic{
public:
    virtual bool is_illegal()=0;
    virtual void calculate()=0;
    virtual void get(double& arg1,double &arg2)=0;
    virtual ~graphic();
};

class graphic2D:public graphic {
protected:
    double area;
    double perimeter;
public:
    virtual void calculate();
    virtual void get(double& arg1,double &arg2);
    virtual void cal_area() = 0;
    virtual void cal_perimeter() = 0;
    virtual bool is_illegal();
    double get_area();
    double get_perimeter();
    graphic2D();
    virtual ~graphic2D();
};

class circle :public graphic2D {
private:
    double r;
public:
    virtual void cal_area();
    virtual void cal_perimeter();
    virtual bool is_illegal();
    circle();
    void set_size(double R);
    virtual ~circle();
};

class triangle :public graphic2D {
private:
    double a, b, c;
public:
    virtual bool is_illegal();
    virtual void cal_area();
    virtual void cal_perimeter();
    triangle();
    void  set_size(double a,double b,double c);
    virtual ~triangle();
};

class rectangle :public graphic2D {
private:
    double w, l;//w即width,l即length
public:
    virtual bool is_illegal();
    virtual void cal_area();
    virtual void cal_perimeter();
    rectangle();
    void set_size(double w, double l);
    virtual ~rectangle();
};

class graphic3D:public graphic {
protected:
    double area;
    double volume;
public:
    virtual void calculate();
    virtual void get(double& arg1,double &arg2);
    virtual bool is_illegal();
    virtual void cal_area() = 0;
    virtual void cal_volume() = 0;
    double get_area();
    double get_perimeter();
    double get_volume();
    graphic3D();
    virtual ~graphic3D();
};

class sphere :public graphic3D {
private:
    double R;
public:
    virtual bool is_illegal();
    virtual void cal_area();
    virtual void cal_volume();
    sphere();
    void set_size(double r);
    virtual ~sphere();
};

class cubic :public graphic3D {
private:
    double w, l, h;
public:
    virtual bool is_illegal();
    virtual void cal_area();
    virtual void cal_volume();
    cubic();
    void set_size(double w, double l, double h);
    virtual ~cubic();
};

class cylinder :public graphic3D {
private:
    double R;
    double h;
public:
    virtual bool is_illegal();
    virtual void cal_area();
    virtual void cal_volume();
    cylinder();
    void set_size(double r,double h);
    virtual ~cylinder();
};
#endif //!GRAPHIC_H

graphic.cpp

```c++

include "graphic.h"

void circle::cal_area() { area=PIrr; }

void circle::cal_perimeter() { perimeter = 2 PI r; }

bool circle::is_illegal() { if (r >= 0) { return true; } else { return false; } }

circle::circle() { r = 0; }

void circle::set_size(double R) { r = R; }

circle::~circle() {

}

void graphic2D::calculate() { cal_area(); cal_perimeter(); }

void graphic2D::get(double &arg1, double &arg2) { arg1=get_area(); arg2=get_perimeter(); }

bool graphic2D::is_illegal() { return true; }

double graphic2D::get_area() { return area; }

double graphic2D::get_perimeter() { return perimeter; }

graphic2D::graphic2D() { area = 0; perimeter = 0; }

graphic2D::~graphic2D() {

}

bool triangle::is_illegal() { { if ((a + b > c) && (a + c > b) && (b + c > a) && a>0 && b>0 && c>0) { return true; } else { return false; } } }

void triangle::cal_area() { double p = (a + b + c) / 2; area=sqrt(p (p - a) (p - b) * (p - c)); }

void triangle::cal_perimeter() { perimeter = a + b + c; }

triangle::triangle() { a = 0; b = 0; c = 0; }

void triangle::set_size(double a, double b, double c) { this->a = a; this->b = b; this->c = c; }

triangle::~triangle() {

}

bool rectangle::is_illegal() { if (w > 0 && l > 0) { return true; } else { return false; } }

void rectangle::cal_area() { area = w * l; }

void rectangle::cal_perimeter() { perimeter = 2 * (w + l); }

rectangle::rectangle() { w = 0; l = 0; }

void rectangle::set_size(double w, double l) { this->w = w; this->l = l; }

rectangle::~rectangle() {

}

void graphic3D::calculate() { cal_area(); cal_volume(); }

void graphic3D::get(double &arg1, double &arg2) { arg1=get_area(); arg2=get_volume(); }

bool graphic3D::is_illegal() { return true; }

double graphic3D::get_area() { return area; }

double graphic3D::get_volume() { return volume; }

graphic3D::graphic3D() { area = 0; volume = 0; }

graphic3D::~graphic3D() {

}

bool sphere::is_illegal() { if (R >= 0) { return true; } else { return false; } }

void sphere::cal_area() { area = 4 PI R * R; }

void sphere::cal_volume() { volume = 4.0 / 3.0 PI pow(R, 3); }

sphere::sphere() { R = 0; }

void sphere::set_size(double r) { R = r; }

sphere::~sphere() {

}

bool cubic::is_illegal() { if (w > 0 && l > 0 && h > 0) { return true; } else { return false; } }

void cubic::cal_area() { area = 2 (w l + w h + l h); }

void cubic::cal_volume() { volume = w l h; }

cubic::cubic() { w = 0; l = 0; h = 0; }

void cubic::set_size(double w, double l, double h) { this->w = w; this->l = l; this->h = h; }

cubic::~cubic() {

}

bool cylinder::is_illegal() { if (R > 0 && h > 0) { return true; } else { return false; } }

void cylinder::cal_area() { area = 2 PI pow(R, 2) + 2 PI R * h; }

void cylinder::cal_volume() { volume = PI pow(R, 2) h; }

cylinder::cylinder() { R = 0; h = 0; }

void cylinder::set_size(double r, double h) { this->R = r; this->h = h; }

cylinder::~cylinder() {

}

graphic::~graphic() {

}

  [1]: http://www.fengdaxian.xyz/usr/uploads/2022/05/3818511942.png