Remove and delete pointers that match a condition in a vector - c++

Question

I have a std::vector that I would like to remove pointers from the vector that meet the condition isDestroyed(), but also call delete on the pointers.
I did the following, but it requires looping over the vector twice. Is there a more efficient way to do it?
std::vector<GameObject*> gameObjects;
std::vector<GameObject*> destroyedObjects;
// Get objects to be deleted
std::copy_if (gameObjects.begin(), gameObjects.end(), std::back_inserter(destroyedObjects), [](GameObject* b){return b->isDestroyed();} );
// Remove objects from vector
gameObjects.erase(
std::remove_if(
gameObjects.begin(),
gameObjects.end(),
[](GameObject* p) { return p->isDestroyed(); }
),
gameObjects.end()
);
// Delete the objects
for (GameObject* o : destroyedObjects)
delete o;

Answer 1

std::unique_ptr does the deletion for free:
std::vector<std::unique_ptr<GameObject>> gameObjects;
// Remove objects from vector
gameObjects.erase(
std::remove_if(
gameObjects.begin(),
gameObjects.end(),
[](const auto& p) { return p->isDestroyed(); }
),
gameObjects.end()
);
I suggest to use it instead. It also avoids mistakes like forgetting to delete or double deleting.

Answer 2

This should work:
std::vector<GameObject*> gameObjects;
auto end = std::stable_partition(
gameObjects.begin(),
gameObjects.end(),
[](GameObject* p) { !return p->isDestroyed(); }
);
for (auto i = end; i < gameObjects.end(); i++) {
delete *i;
}
gameObjects.erase(end, gameObjects.end());

Answer 3

You don't need 2 vectors. The iterator returned by std::remove_if() can be used to know which objects need to be delete'd:
std::vector<GameObject*> gameObjects;
...
auto newEnd = std::remove_if(
gameObjects.begin(), gameObjects.end(),
[](GameObject* p) { return p->isDestroyed(); }
);
for(auto iter = newEnd; iter != gameObjects.end(); ++iter) {
delete *iter;
}
gameObjects.erase(newEnd, gameObjects.end());
If you change your vector to hold std::unique_ptr<GameObject> instead of GameObject*, you don't need to delete the objects manually anymore:
std::vector<std::unique_ptr<GameObject>> gameObjects;
...
gameObjects.erase(
std::remove_if(
gameObjects.begin(), gameObjects.end(),
[](std::unique_ptr<GameObject> &p) { return p->isDestroyed(); }
),
gameObjects.end()
);