I have a structure :

struct node
{
    QPoint position;
    QVector<node> neighbours;

    void add(QPoint);
    void addNeighbours(QVector<node>);

    ...
};

With methods :

void node::add(QPoint p)
{
    position = p;
}

void node::addNeighbours(QVector<node> n)
{
    neighbours = n;
}

However when I try to use addNeighbours I get the following error :

error: C2662: 'node::addNeighbours' : cannot convert 'this' pointer from 'const node' to 'node &'
Conversion loses qualifiers

From looking online I think the solution comes from; using the correct pointers and possibly by the QVectors::Iterator(). Although I cannot come up with a solution, any pointer in the right direction or an explanation on why this is happening is greatly appreciated.

Main:

int main(int argc, char *argv[])
{
    QVector<node> map;
    QVector<node> tmp;
    node n;

    //Populate map
    for(int i = 0; i < 3; i++)
        for(int j = 0; j < 3;  j++)
        {
            n.add(QPoint(i,j));
            map.append(n);
        }

    //Add required nodes to tmp
    tmp.append(map.at(1));
    tmp.append(map.at(3));

    //Set the neighbour nodes of map(0) using tmp vector
    map.at(0).addNeighbours(tmp);
}

Change

map.at(0).addNeighbours(tmp); // at() : returns a const reference

map[0].addNeighbours(tmp); // [] : returns a non-const reference

Also, it's better to change addNeighbours to this:

 void node::addNeighbours(const QVector<node> &n)