Vector Collision - c++

Question

I am quite green regarding vectors, and this is my first time actually using them for collision checking. This is for my project, and I am stumped on how to implement the collision. The current Collision check and response codes I have seem to be ... bad design.
This is my code:
for(auto it = ArrayofEntities.begin(); it != ArrayofEntities.end(); it++)
{
CEntity * go = (*it);
for(auto i = ArrayofEntities.begin(); i != ArrayofEntities.end();)
{
//Collision for entities. Collision Event returns the iterator after an element is erased.
CEntity * other = (*i);
if (go != other)
{
if (!theCollision.CheckCollision(go, other, false, false, false, false)) //Checks if it has collided go with other
{
i = go->CollisionEvent(*other, ArrayofEntities); //Run collision code, setting i to the iterator which is returned.
//break;
}
else
{
i++;
}
}
else
{
i++;
}
}
}
CEntity is the base class for all the entities.
My CheckCollision just returns a true or false on the collision, and my collision event runs the collision and returns an iterator (because I might have to destroy things in the vector).
My collision event is below
vector<CEntity*>::iterator bullet::CollisionEvent(CEntity &other, vector<CEntity*> & theArray)
{
case ZOMBIE:
{
other.hp -= power * 0.01;//Effect
int Counter, index, bulletindex;
auto it = theArray.begin();
//Find the bullet and the other in the array.
for (it = theArray.begin(), Counter = 0; it != theArray.end();it++, Counter++)
{
CEntity *go = NULL;
go = (*it);
if (go == &other)
{
index = Counter;
}
if(go->ID == BULLET && go->GetX() == GetX() && go->GetY() == GetY())
{
bulletindex = Counter;
}
}
this->~bullet();//Delete the bullet
theArray.erase(theArray.begin() + bulletindex);
if(other.hp <= 0)
{
other.~CEntity();
it = theArray.erase(theArray.begin() + index); //delete from array.
return it;
}
it = theArray.begin() + index;
return it;
}
}
I have basically done this like how I would do an array. Just check it against itself. The error it gives is "Vector Iterator not Incrementable", on the first for loop after the collision event has been run.
So my question: 1) What am I doing wrong?
2) Is my thinking to do this like checking arrays wrong?
This is my school project, so I have full control of the codes.
I would prefer to have a quick fix over a complete rewriting of all the collision codes, but if it really comes down to it, I will rewrite my codes.

Answer 1

If you look at the implementation of std::remove_if, you'll see that they've solved the issue of iterator invalidation in another way. instead of erasing elements, they move them to the end of the array.
This may be the easiest solution for you as well. Keep an iterator which points after the last "live" entirty. It starts out at .end but as bullets hit things, you swap the entities to the back of your range and decrement that last-live iterator.
Then, when you're done looping over your array, you clean up with a single call to .erase.
And yes, you should use either std::unique_ptr<CEntity> or std::shared_ptr<CEntity> in the collection. In that way, .erase won't just erase the pointer but also the object pointed to.