Null Reference Exception due to another array in C# script

Question

I've created an array randomNumbersList which I'm going to access through Unity Inspector. And I want to assign the size of this array to my second array evenNumberList, probably which is the reason of this error at code line evenNumberList[i] = randomNumbersList[i];

public class Basics : MonoBehaviour
{
    public int[] randomNumbersList;
    int[] evenNumberList;
    bool numberFounded;
    int evenNumbers = 0;
    int duplicateNumber;
    int numberOfEvens = 0;

    void Start()
    {   
        SearchNumber();
        FindEvenNumbers();
        FindMaxMinNumber();
        FindMaxMinEvenNumber();
    }

    void FindEvenNumbers()
    {
        for (int i = 0; i < randomNumbersList.Length; i++)
        {
            if (randomNumbersList[i] == duplicateNumber)
                Debug.Log("Number " + randomNumbersList[i] + " Already Exists...");
            else
            {
                if (randomNumbersList[i] % 2 == 0)
                {
                    evenNumberList[i] = randomNumbersList[i];
                    duplicateNumber = randomNumbersList[i];

                    for (int j = 0; j < randomNumbersList.Length; j++)
                    {
                        if (duplicateNumber == randomNumbersList[j])
                            ++numberOfEvens;
                    }

                    Debug.Log(randomNumbersList[i] + " is an Even Number, founded at index " + i + " and it appears " + numberOfEvens + " times");
                    numberOfEvens = 0;

                    ++evenNumbers;
                }
            }
        }

        Debug.Log("Total " + evenNumbers + " Even Numbers have been Founded");
    }

How do you instantiate `evenNumberList`? I guess `randomNumbersList`is being assigned in the not shown method `SearchNumbers()`. When using `evenNumberList` without any value, you'll get a nullreferenceexception on `null[i]` — Chrᴉz remembers Monica, Nov 25 '20 at 12:33
Does this answer your question? [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Thomas, Nov 25 '20 at 12:35
@ChrᴉzsupportsMonica the `randomNumbersList` will be initialized by Unity anyway since it is serialized ;) — derHugo, Nov 25 '20 at 13:51

score 0 · Accepted Answer · answered Nov 25 '20 at 12:37

0

Initialize evenNumberList in the Start method

void Start()
{
  evenNumberList = new int[randomNumbersList.Length];
  ...

answered Nov 25 '20 at 12:37

davobutt

161
2

Null Reference Exception due to another array in C# script

1 Answers1