Vector of objects and Iterator

[Ivan Novák]

hi, I am getting runtimes errors sometimes and cant figure out why, that i am pointing on wrong memory.
i have got this terrible interface. I think there can be problem with saving objects to vector and my copy constructor, or iterator. And i am not sure if i am saving those files correctly.

Thanks for any help.

I have class Airport which has vector of planes.

vector<plane> planes;
vector<plane>::iterator planeIterator;


bool airport::addPlane(const plane& p)   //funcction to add planes into vector
{
    if(planes.empty())
    {
        planes.push_back(p);
        planeIterator = planes.begin();     //if vector empty put iterator on first object
    }
    else
    {
        planes.push_back(p);
    }
    return true;
}

const plane* airport::getCurrentPlane() const    // get the current object on which is iterator pointing has to be const pointer on plane
{
    if(planes.size()== 0)
    {
        return NULL;
    }
    plane *p1 = new plane(*planeIterator);


    return p1;
}

//here is my copy constructor from plane class
plane::plane(const plane& other)
{
    _name=other.getName();
    other.getPosition(_x,_y);
    _direction=other.getDirection();
    _hasLanded = other._hasLanded;
}

[grumpy]

Any operation that changes number of elements in a vector - such as push_back() - can invalidate all iterators related to that vector.

Every call to plane.push_back() therefore needs to be followed up by "planeIterator = plan.begin()". Similarly with any operation that removes elements from the plane vector.

[kmdv]

I worry that you declared these variables as global:

vector<plane> planes;
vector<plane>::iterator planeIterator;

I hope you only wanted to make this code snippet as small as possible. If you did not, you should make them members of `airport`.
Remember to also properly implement copy constructor and copy-assignment operator of `airport`, or prohibit its copying at all.

And seriously consider using an index instead of an iterator - you will avoid many errors and you will be able to use the default copy constructor/copy-assignment operator.

[Elysia]

I would also advice you to get rid of the new. Just return a const reference to the object pointed to by the iterator (or in this case, always .begin())!