lvalue.cpp

#include <iostream>

using namespace std;

class Point {

public:
    int _x;
    int _y;

    Point(int x, int y) : _x(x), _y(y) {}

    int& x() { return this->_x; }

    int& y() { return this->_y; }
};

int main() {
    Point p(1, 2);

    cout << p.x() << endl;
    p.x() += 1;
    cout << p.x() << endl;

    return 0;
}