How do i insert objects into STL set

Question

I am trying to insert a object Point2D into a Point2D set but i am not able to do it, it seems the set works for int and char but not for objects.

I need help to kn

Answer 1

I believe a better way for C++ 11 or newer to define the order is to use custom functor, since std::set support that.

We can see set is defined in header like this:

template<
    class Key,
    class Compare = std::less,
    class Allocator = std::allocator
> class set;

Hence, to compare based on x for example:

struct Point2DCmp
{
    bool operator() (Point2D& p1, Point2D& p2)
    {
        return p1.getX() < p2.getX();
    }
}

set P2D;