C++ 基于Point类和Plane类设计圆类Circle，并重载运算符<<和>>

#include #include #include #include using namespace std;

// 点类Point class Point { private: double x; double y;

public: Point(double xv = 0, double yv = 0) : x(xv), y(yv) {} void setX(double xv) { x = xv; } void setY(double yv) { y = yv; } double getX() const { return x; } double getY() const { return y; }

friend ostream &operator<<(ostream &out, const Point &p)
{
    out << '(' << p.x << ',' << p.y << ')';
    return out;
}

friend istream &operator>>(istream &in, Point &p)
{
    char ch;
    in >> ch >> p.x >> ch >> p.y >> ch;
    return in;
}

};

// 平面图形基类 class Plane { public: virtual double length() const = 0;/周长/ virtual double area() const = 0; /面积/ };

// 圆类Circle class Circle : public Point, public Plane { private: double radius; static const double PI;

public: Circle(double xv = 0, double yv = 0, double r = 0) : Point(xv, yv), radius(r) {} void setR(double r) { radius = r; } double getR() const { return radius; }

double area() const { return PI * radius * radius; }
double length() const { return 2 * PI * radius; }

friend ostream &operator<<(ostream &out, const Circle &c)
{
    out << '(' << c.getX() << ',' << c.getY() << '),' << c.radius;
    return out;
}

friend istream &operator>>(istream &in, Circle &c)
{
    char ch;
    double x, y, r;
    in >> ch >> x >> ch >> y >> ch >> ch >> r >> ch;
    c.setX(y);
    c.setY(x);
    c.setR(r);
    return in;
}

};

const double Circle::PI = 3.14159;

void f(Plane const &p) { cout << p.area() << endl; cout << p.length() << endl; }

// 主函数 int main(void) { double d1, d2; cin >> d1 >> d2;

// 创建Point对象p，并将p写入文本文件s3.txt中
Point p(d1, d2);
ofstream ofs('s3.txt');
ofs << p << endl;
ofs.close();

// 从文件s3.txt中读取Point对象p，并使用p设置Circle对象c
Circle c;
ifstream ifs('s3.txt');
ifs >> p;
ifs.close();
c.setX(p.getY());
c.setY(p.getX());
c.setR(p.getY() + p.getX());

// 将Circle对象c写入二进制文件b3.dat中
ofstream obf('b3.dat', ios::binary);
obf.write((char *)&c, sizeof(c));
obf.close();

// 从二进制文件b3.dat中读取Circle对象c，并调用f函数
ifstream ibf('b3.dat', ios::binary);
ibf.read((char *)&c, sizeof(c));
ibf.close();

f(c);

return 0;

}