Operator Overloading

C++ lets you define what an operator like + means for your own type, by implementing a method named operator+. This is genuinely distinctive compared to every other course on this site: Python has dunder methods for a similar purpose, but no other language here lets a type opt into the exact same operator syntax built-in numeric types use.

#include <iostream>
using namespace std;

class Point {
public:
    int x, y;

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

    Point operator+(const Point& other) const {
        return Point(x + other.x, y + other.y);
    }
};

int main() {
    Point a(1, 2);
    Point b(3, 4);
    Point c = a + b;
    cout << "(" << c.x << ", " << c.y << ")" << endl;
    return 0;
}

(4, 6)

a + b calls a.operator+(b) behind the scenes — the syntax reads exactly like adding two numbers, even though Point is a type you defined. The : x(x), y(y) syntax in the constructor is a member initializer list, the idiomatic way to set a C++ class's fields directly from its constructor parameters.

Next: templates — C++'s own compile-time mechanism for writing one function or class that works across many types.