Things to note when deleting list elements in a loop
If you’re looping through a list and want to remove elements from that list, loop around ** in reverse order **.
NG
for (int i = 0; i < enemyList.Count; i++) {
if (!enemyList[i].IsAlive) {
enemyList.RemoveAt(i);
}
}
OK
for (int i = enemyList.Count - 1; i >= 0; i--) {
if (!enemyList[i].IsAlive) {
enemyList.RemoveAt(i);
}
}
Why do we have to reverse the order? The figure below shows. On the NG side, when the element C is deleted, the element behind it is packed to the front, causing the problem that the element D is not processed correctly.
By the way, RemoveAll is useful when you want to remove an element of a list but you don’t need to do it ** in a loop **.
python
enemyList.RemoveAll(enemy => !enemy.IsAlive);