c++ - 从 Circle 类 C++ 返回 bool 值

Question

我正在尝试使用 C++ 类返回一个 bool 值。它需要能够使用重载运算符 > 来检查圆 A 是否与圆 B 大小相同，我已将其添加为类中的公共(public)成员。在我的 int main 中，即使圆圈大小相同，它似乎也总是返回 false。

提前致谢。

圈类:

#include <iostream>
#include <cmath>

using namespace std;

//creating a constant pi that can't be changed
const double pi = 3.14159265;

class Circle
{
    //defining the private memeber variables
    private:
            double radius, xpos, ypos;

    //defining the public member variables
    public:
            //creating a constructor that takes all of the variables
            Circle(double r, double xposition, double yposition) {
                radius = r;
                xpos = xposition;
                ypos = yposition;
            }

            //creating a constructor that takes just the radius  
            Circle(double r) {
                radius = r;
                xpos = 0;
                ypos = 0;
            } 

            //creating a contructor that initialised everything to 0
            Circle() {
                radius = 0;
                xpos = 0;
                ypos = 0;
            }

            //defining the functions for radius, X-position, Y-position and area                       
            double getRadius() {return radius;}
            double getX() {return xpos;}
            double getY() {return ypos;}
            double getArea() {return pi*radius*radius;}

            //creating an overaload operator + to add the various properties of a circle together
            Circle operator+(Circle C) {
                radius = sqrt(this->getRadius()*this->getRadius() + C.getRadius()*C.getRadius()); //calculates the radius from the area
                xpos = (this->getX() + C.getX()) / 2.; //calculating the half way x position
                ypos = (this->getY() + C.getY()) / 2.; //calculating the half way y position
                return Circle(radius, xpos, ypos);
            } 

            //created an overload operator << that outputs information about the circle in a consistent manor
            friend ostream& operator<<(ostream& os, Circle C) {
                return os << "radius = " << C.getRadius() << " at (x,y) = (" << C.getX() << "," << C.getY() << ")";
            }

            bool operator>(Circle C) {
                if (this->getRadius() > C.getRadius()) {
                    return true;
                }
                else {
                    return false;
                }
            }
};

Int main()

#include "Circle.hpp"

using namespace std;

int main()
{
    //defining the circles A and B
    Circle A(4.0,2.0,1.0);
    cout << "Circle A: " << A << endl;

    Circle B(4.0,5.0,6.0);
    cout << "Circle B: " << B << endl;

    //Adds A and B using the overload operator +
    Circle C = A + B;

    //Outputs the formatted text using the overload operator <<
    cout << "Circle C: " << C << endl;


    bool test;
    Circle D(4.0,2.0,1.0);

    if (A > D) {
        test = false;
    }
    else if (D > A) {
        test = false;
    }
    else {
        test = true;
    }

    cout << boolalpha << test << endl;

    return 0;
}

Answer 1

A.r 是 4.0。 D.r 也是 4.0。 D > A 和 A > D 都不为真。 > 检查实际是否大于。如果你想要大于等于使用 >= 代替。