array index out of range?

Unity Engine
1

hello.

I have this code for an wave spawner script.
in the array _monster i have 3 enemy’s

and in the spawnpoint i have 4 spawnpoint.

but when i want to spawn the 4th enemy because it should do that it says array index is out of range.

using UnityEngine;
using System.Collections;

public class wavescript : MonoBehaviour{
   
    public GameObject[] _monster;
    public Transform[] _spawnPoints;
    // know your ennemy :)
    private string _monsterName;
    // 2 seconds between each spawn
    private float delayTime = 2f;
    private int _oO = 0;
    // we start easy with 2 enemies
    private int _nbrMonster = 10;
   
    IEnumerator Start(){
       
        int i = 0; //restart
        // loop to create a wave using _nbrMonster
        for (i = 0; i < _nbrMonster; i++){
            Transform pos = _spawnPoints[_oO];

            Instantiate(_monster[i], pos.position, pos.rotation);
            // I know his name
            _monsterName = _monster[i].name;
            // change spawnPoint
            _oO ++;
            if(_oO >= _spawnPoints.Length)_oO = 0;
            // wait a moment
            yield return new WaitForSeconds(delayTime);
        }
    }
   
    void Update(){
        // while the last enemy lives always we wait
        if(!GameObject.Find(_monsterName+("(Clone)"))){
            _nbrMonster = _nbrMonster + 2; // increase +2
            if(_nbrMonster > 20)_nbrMonster = 20; // maximum occurence
            StartCoroutine(Start()); // new wave
        }
    }
}

i’m not really good in unity so can anybody help me?

2

When you calculate the length, you get the total number of items (4).
But when you access your spawn point you start at index 0 (so => 0,1,2,3)
You need to change that line :

// if(_oO >= _spawnPoints.Length)_oO =0;
// by 
if(_oO >= _spawnPoints.Length-1)_oO =0;
3

Actually, the following should be fine:

if (_oO >= _spawnPoints.Length) _oO = 0;

Since a collection with 4 items:

0: Item 1
1: Item 2
2: Item 3
3: Item 4

and the values of _oO:

// _oO is 0

++_oO;
if (_oO >= 4) _oO = 0;
// _oO is 1

++_oO;
if (_oO >= 4) _oO = 0;
// _oO is 2

++_oO;
if (_oO >= 4) _oO = 0;
// _oO is 3

++_oO;
if (_oO >= 4) _oO = 0;
// _oO is 0

The value of _oO doesn’t go out-of-bounds.

At the start of the function add the following to verify the initial state of the game:

    IEnumerator Start(){
       // Is the initial value as expected?
       Debug.Log("_oO: " + _oO);
       // Are there actually any spawn points in the array?
       Debug.Log("Spawn Points Length: " + _spawnPoints.Length);
       // Are there enough monsters?
       Debug.Log("Monster Length: " + _monster.Length);