2023.4.20记录2

定义基类Point（点）和派生类Circle（圆），求圆的周长。Point类有两个私有的数据成员float x,y;Circle类新增一个私有的数据成员半径float r和一个公有的求周长的函数getCircumference();主函数已经给出，请编写Point和Circle类。

输入格式:

输入圆心和半径，x y r中间用空格分隔。

输出格式:

输出圆的周长，小数点后保留2位有效数字。

输入样例:

1 2 3

输出样例:

在这里给出相应的输出。例如：

Point constructor called
Circle constructor called
18.84
Circle destructor called
Point destructor called

#include <iostream>
#include<iomanip>
using namespace std;

class Point
{
private:
float x;
float y;
public:
Point(float x, float y)
{
this->x = x;
this->y = y;
cout << "Point constructor called" << endl;
}
~Point()
{
cout << "Point destructor called" << endl;
}
};
class Circle : public Point
{
private:
float r;
public:
Circle(float x, float y, float r) :Point(x, y)
{
this->r = r;
cout << "Circle constructor called" << endl;
}
double getCircumference()
{
return 2 * 3.14 * r;
}
~Circle()
{
cout << "Circle destructor called" << endl;
}
};
int main()
{
float x, y, r;
cin >> x >> y >> r;
Circle c(x, y, r);
cout << fixed << setprecision(2) << c.getCircumference() << endl;
return 0;
}