point-operations.cpp

/*
 * ============================================================================
 * Topic : Point class (constructors)
 * Level : OOP — constructors
 * ----------------------------------------------------------------------------
 * What you'll learn
 *   Provide default and parameterized constructors for a 2D Point.
 *   Implement vector addition that returns a new Point.
 *   See initializer lists (: x(x1), y(y1)) in action.
 * ----------------------------------------------------------------------------
 * How to run
 *   • OnlineGDB: https://www.onlinegdb.com/online_c++_compiler
 *     Open this file on GitHub → copy → paste into OnlineGDB → C++ → Run
 *   • Codespaces (whole repo): https://codespaces.new/baheesa/cpp-practice?quickstart=1
 *   • Local: g++ -std=c++17 -Wall -o app "02-oop/concepts/point-operations.cpp" && ./app
 * ----------------------------------------------------------------------------
 * Example input
 *   (no input — points are hard-coded)
 * Example output
 *   a = (2, 3)
 *   b = (4, 5)
 *   a + b = (6, 8)
 * ============================================================================
 */

#include <iostream>
using namespace std;

class Point {
    int x, y;
public:
    Point() : x(0), y(0) {}                    // default → origin
    Point(int x1, int y1) : x(x1), y(y1) {}    // parameterized via initializer list

    void show() const {
        cout << "(" << x << ", " << y << ")";
    }

    // Return a new Point; neither a nor b is modified (const method + const arg).
    Point add(const Point& p) const {
        return Point(x + p.x, y + p.y);
    }
};

int main() {
    Point a(2, 3), b(4, 5);
    Point c = a.add(b);

    cout << "a = "; a.show(); cout << '\n';
    cout << "b = "; b.show(); cout << '\n';
    cout << "a + b = "; c.show(); cout << '\n';
    return 0;
}