Question

Here is my code:

void SurfaceManager::SurfaceManagerDelete()
{
    for(map<string,SurfaceManager*>::iterator Iter = SurfaceList.begin(); Iter != SurfaceList.end(); ++Iter)
    {
        delete (*Iter).second;

        (Iter) = SurfaceList.erase(Iter);
    }

   SurfaceList.clear();
}

Why does this cause several memory leaks when I scan it with VLD? I know it has something to do with the way I’m deleting the memory from an element specifically this line “(Iter) = SurfaceList.erase(Iter);”, however I would like to know why, and how I’m supposed to properly delete elements from the list.

Answer 1

The problem is the ++Iter in the for-loop. That’s because

(Iter) = SurfaceList.erase(Iter);

already updates Iter to point to the element after the erased one, like an increment.

So the ++Iter then skips another element, effectively you end up deleting every other element!