问重载的Circle()在C++ Circle类中不明确

EN

#include <iostream>

using namespace std;

const double pi = 3.14159265;

class Circle
{
    private:
            double radius, xpos, ypos, area;

    public:
            Circle(double r, double xposition, double yposition) {
                r = radius;
                xposition = xpos;
                yposition = ypos;
            }

            Circle(double r = 0) {
                radius = r;
                xpos = 0;
                ypos = 0;
            } 

            Circle() {
                radius = 0;
                xpos = 0;
                ypos = 0;
            }

            double getRadius() {return radius;}
            double getX() {return xpos;}
            double getY() {return ypos;}
            double getArea() {return pi*radius*radius;}

            Circle operator+(const Circle& c) {
                Circle circle;
                circle.area = this -> getArea() + c.getArea();
                return circle;
            } 
};


int main()
{
    Circle circ(3,2,1);
    double x = circ.getX();
    cout << x << endl;
    return 0;
}