Résultat surprenant

#include <iostream>
#include <cmath>

using namespace std;

class point
{
public:
    point(int abscisse, int ordonnee)
    {
        x = abscisse;
        y = ordonnee;
    };
    int abscisse() {return x; }
    int ordonnee() {return y; }

private:
int x;
int y;
};

class segment
{
  public:
    segment(point a, point b)
    {
        debut = &a;
        fin = &b;
    };

    double l1()
    {
        return debut->abscisse();
    }

 double l2()
    {
        return debut->ordonnee();
    }

 double l3()
    {
        return fin->abscisse();
    }

 double l4()
    {
        return fin->ordonnee();
    }

  private:
  point * debut;
  point * fin;
};

int main()
{
    point a(1,2), b(3,4);
    segment ab(a,b);
    cout << "Abscisse de a : " << a.abscisse() << ", ordonnee de a : " << a.ordonnee() << endl;
    cout << "Abscisse de b : " << b.abscisse() << ", ordonnee de b : " << b.ordonnee() << endl;
    cout << "Longueur de [ab] : " << ab.l1() << " " << ab.l2() << " " << ab.l3() << " " << ab.l4();
    return 0;
}

Abscisse de a : 1, ordonnee de a : 2
Abscisse de b : 3, ordonnee de b : 4
Longueur de [ab] : 4.61813e+006 2 3 4

segment(point* a, point* b)
{
    debut = a;
    fin = b;
};

point a(1,2), b(3,4);
segment ab(&a, &b);

segment(const point& a, const point& b)
{
    debut = new Point(a.abscisse(), a.ordonnee());
    fin = new Point(b.abscisse(), b.ordonnee());
};

// et utiliser un destructeur

~segment()
{
    if(debut) delete debut;
    if(fin) delete fin;
}