C++ 设计一个圆类，计算圆的面积和周长。

Posted 2023-03-15

1.定义一个园（circle)，属性为半径（radins)、圆周长和面积，操作为输入半径并计算周长、面积、输出半径和面积。要求定义构造函数（以半径为参数。默认值为0，周长和面积在构造函数中生成）和复制构造函数。

2.定义一个point类，派生出Rectangle类和Circle类，计算各派生类对象的面积。

3.有一个交通工具类vehicle，将它作为基类派生小车类car，卡车类truck和轮船类boat，定义这些类并定义一个虚函数用来显示各类信息。

三道路题目解决下，谢谢各位了 ,一题10分

1.
class Circle

public:
Circle():r(0), leng(0), area(0)

Circle(const int rm):r(rm)
leng = 2 * pi * rm;
area = pi * rm * rm;

Circle& Circle(Circle& other)
r = other.r;
leng = other.leng;
area = other.area;
return *this;


void setR(const double rm)

r = rm;
leng = 2 * pi * r;
area = pi * r * r;

void output()

cout<<"r is "<<r<<", "<<"area is "<<area<<endl;


private:
double r;
double leng;
double area;
;
2.
#include <iostream>
using namespace std;

const double pi = 3.14;
//Point类，派生出Rectangle类和Circle类，计算各派生类对象的面积Area（）。
template <class T>
class Point

public:
Point()
Point(const T x, const T y);
Point& operator= (const Point<T>&p);

public:
T x;
T y;
;

template <class T>
Point<T>::Point(const T x, const T y)

this->x = x;
this->y = y;

template <class T>
Point<T>& Point<T>::operator= (const Point<T>&p)

this->x = p.x;
this->y = p.y;
return *this;


template <class T>
class Shape

public:
virtual double Area() = 0;
;
template <class T>
class Rectangle:public Shape<T>

public:
Rectangle(const Point<T>& p1, const Point<T>& p2);
double Area();
private:
Point<T> pLT;
Point<T> pRD;
;

template <class T>
Rectangle<T>::Rectangle(const Point<T>& p1, const Point<T>& p2)

pLT = p1;
pRD = p2;

template <class T>
double Rectangle<T>::Area()

T w = pLT.x - pRD.x;
T h = pLT.y - pRD.y;
if(w<0) w = -w;
if(h<0) h = -h;
return double(w * h);

//Circle
template <class T>
class Circle:public Shape<T>

public:
Circle(const Point<T>& p1, const T& r);
double Area();
private:
Point<T> origin;
T r;
;

template <class T>
Circle<T>::Circle(const Point<T>& p1, const T& r)

origin = p1;
this->r = r;

template <class T>
double Circle<T>::Area()

return pi * r * r;

int main()

Point<int> p1(9, 0);
Point<int> p2(1, 2);
Rectangle<int> R(p1, p2);
Circle<int> C(p1, 10);
printf("Rectangle ' Area is %f\n", R.Area());
printf("Circle ' Area is %f\n", C.Area());
return 0;

3.
#include <iostream>
using namespace std;

class vehicle

public:
virtual void run()cout<<"vehicle is run."<<endl;
;
class Car:public vehicle

public:
void run()cout<<"Car is run."<<endl;
;

inclass truck:public vehicle

public:
void run()cout<<"truck is run."<<endl;
;
class boat:public vehicle

public:
void run()cout<<"boat is run."<<endl;
;

int main()

vehicle *p1 = new Car;
p1->run();
vehicle *p2 = new truck;
p2->run();

vehicle *p3 = new boat;
p3->run();
vehicle *p4 = new vehicle;
p4->run();

delete p1;
delete p2;
delete p3;
delete p4;

return 0;
参考技术A #include<iostream>
#include<cmath>
using namespace std;
class Circle
double r,Area,Circumference;
public:
Circle(double a=0);
Circle(Circle &);

void SetR(double R);
double GetR()return r;
double GetAreaCircle()return Area;
double GetCircumference()return Circumference;
;
Circle::Circle(double a)
r=a;
Area=r*r*3.14159265;
Circumference=2*r*3.14159265;

Circle::Circle(Circle & cl)
r=cl.r;
Area=cl.Area;
Circumference=cl.Circumference;


void Circle::SetR(double R)
r=R;
Area=r*r*3.14159265;
Circumference=2*r*3.14159265;

第二个我还不熟悉写,我尽力了.不采纳没关系