명품 C++ Programming 실습문제 7장 8번

#include <iostream>
using namespace std;
 
class Circle {
    int radius;
public:
    Circle(int radius = 0) { this->radius = radius; }
    void show() { cout << "radius = " << radius << " 인 원" << '\n'; }
    friend Circle operator+(int x, Circle a);
};
 
Circle operator+(int x, Circle a) {
    a.radius += x;
    return a;
}
 
int main() {
    Circle a(5), b(4);
    b = 1 + a;
    a.show();
    b.show();
}