Question

I have the code:

class Vector3D : public Vector{
protected:
    Point3D * start;
    Point3D * end;

public:
    ~Vector3D(){delete start; delete end;}
    Vector3D(Point3D * start, Point3D * endOrLength, bool fromLength){
        this->start = start;
        if(fromLength){
            this->end = new Vector3D(*start+*endOrLength); //the operator '+' is defined but I won't put it here,
            //because it's not important now
        }else
            this->end = endOrLength;
    }

    Point3D * getStart(){return start;}
    Point3D * getEnd(){return end;}
};

Now, I have the code:

Vector3D v(new Point3D(1,2,3), new Point3D(2,3,4), 0); //FIRST CREATION
Vector3D v(new Point3D(1,2,3), new Point3D(1,1,1), 1); //SECOND CREATION

First and Second creation give me the same Vector3D, but I think it may produce memory leaks.

It’s a true? And how to solve it? I guess it’s not elegant to make it that way:

...
if(fromLength){
    this->end = new Vector3D(*start+*endOrLength);
    delete endOrLength;
}else
...

Maybe it’s better to put const Point3D &endOrLenght, I don’t know what would be a good mannier? The same with getStart/getEnd – should it return pointer:

Point3D * getStart(){return start;}

or just the variable:

Point3D getStart()(return *start)

?

Answer 1

You code here may not be the best way of handling this, but to directly fix your problem:

Vector3D(Point3D * start, Point3D * endOrLength, bool fromLength){
    this->start = start;
    if(fromLength){
        this->end = new Vector3D(*start+*endOrLength); // I think you mean to use endOrLength here and not length.
        if (endOrLength)
            delete endOrLength;
    }else
        this->end = endOrLength;
}

---

I think a better solution to your problem is to use smart pointers, and the best solution is to see if you can replace pointers.

class Vector3D : public Vector
{
protected:
    Point3D _start;
    Point3D _end;

public:
    Vector3D(const Point3D& start, const Point3D& endOrLength, bool fromLength) :
    _start(start),
    _end(fromLength ? Vector3D(start + endOrLength) : endOrLength)
    {
    }

    const Point3D& getStart() const { return _start; }
    const Point3D& getEnd() const { return _end; }
};