Delete vector object while in for loop [c++]

Asked Sep 11 '20 at 15:22

Active Sep 11 '20 at 15:28

Viewed 66 times

In my program i have a for loop which updates all the bullets/shots in my game. It looks like this:

for (auto sprite : shots)
{
    sprite->update(shots);
}

In the update function from the class, i delete a shot from the shots list if it detects a collision, like this:

void Shot::terminate(std::vector<Shot*>& shots)
{
    shots.erase(shots.begin() + index /*index is the elements number in the vector "shots"*/);
}

This function "terminate" is called if the update() class function detects a collision. But when a object from the list is deleted while in the for loop; the program crashes "vector subscript out of range". The counter in the for loop should be substracted by 1 every time a object gets deleted but i dont know how to do so in a c++11 for loop. Is it possible to fix my problem?

edited Sep 11 '20 at 15:28

asked Sep 11 '20 at 15:22

Noah.Ehrnstrom

1

What is `index`? Please make a [mre] – cigien Sep 11 '20 at 15:24
Are you ultimately deleting the sprite from the range based for loop? – drescherjm Sep 11 '20 at 15:26
yes, im disappearing it completely. – Noah.Ehrnstrom Sep 11 '20 at 15:27
That's UB, you can't modify a range that you do a range-for loop over. – cigien Sep 11 '20 at 15:28
This seems like a design issue. Why is `Shot` responsible for removing itself(?) from some vector? My first thought is to make it have some `isPresentOnScreen()` function which could be used in `std::remove_if` after the `update` loop. – Yksisarvinen Sep 11 '20 at 15:30
@S.M. Yes it does answer my question – Noah.Ehrnstrom Sep 11 '20 at 15:31

Delete vector object while in for loop [c++]

0 Answers0