Question

What is the correct operator< for the following class?

struct Person {
  int height;
  int width;
  friend bool operator<(const Person&, const Person&);
};

Thanks!

Answer 1

That’s entirely up to you and how you would want people to naturally sort. If you want short people first, but skinny to come before tall if they are the same height:

friend bool operator<(const Person& a, const Person& b) {
    return a.height != b.height ? a.height < b.height : a.width < b.width;
}

If you want some measure of a person’s surface area to determine ordering:

friend bool operator<(const Person& a, const Person& b) {
    return a.height * a.width < b.height * b.width;
}