NullreferenceException on multidimensional array on c#

Question

I have a class with a default constructor , but when I create an array of this class I get a NullReferenceException

using UnityEngine;
using System.Collections;

public class Casilla {
    int _nCasilla { get; set; }
    bool _ocupada { get; set; }
    bool _blanca { get; set; }
    Vector3 posicion;

    public int nCasilla
    {
        get { return _nCasilla; }
        set { _nCasilla = value; }
    }
    public bool ocupada
    {
        get { return _ocupada; }
        set { _ocupada = value; }
    }

    public bool blanca
    {
        get { return _blanca; }
        set { _blanca = value; }
    }

    public Vector3 getPosicion()
    {
        return posicion;
    }
    public void setPosicion(float x, float z){
        posicion.x = x;
        posicion.y = 0;
        posicion.z = z;
    } 

    public Casilla(){
        posicion = new Vector3();
        ocupada = false;
        _blanca = true;
        posicion.x = 0;
        posicion.y = 0;
        posicion.z = 0;
    }
}

public class Tablero  {

    Casilla[,] tablero;
    bool blanca = true;

    public Tablero(){
        tablero = new Casilla[8,8];
        float x, z;
        x = z = 0;

        for (int i=0; i <8; i++){
            for (int j = 0; j < 8; j++){
                tablero[i, j].nCasilla = 8 * i + j;//The exception is here
                tablero[i, j].blanca = blanca;
                tablero[i, j].setPosicion(x, z);
                blanca = !blanca;
                x += 10;
            }
            x = 0;
            z -= 10;
        }
    }
}

I have small experience with C# but when you create a n array in C++ every element of this array is created calling the default constructor of Casilla class has a default constructor. So what is the problem??

C++ is not C#, the default value for every element of an array that holds reference types is `null`. — Preston Guillot, May 02 '16 at 17:37
Check your error log and there you will find the line that gives your error. — Mihai-Daniel Virna, May 02 '16 at 17:38
And yet, the answer is found in the duplicate. Bottom line: you need to initialize your array. — Eric J., May 02 '16 at 17:39
@AFS More specifically, you need to initialize each *element* in your array. — Gabriel Luci, May 02 '16 at 17:41
Simply insert `tablero[i, j] = new Casilla();` as the first line in the nested `for` loop. Without that `tablero[i, j]` will be the null reference. In C# a `class` is a reference type, and so the value of each array entry is a reference. The default value for a reference is `null`. — Jeppe Stig Nielsen, May 02 '16 at 21:57

NullreferenceException on multidimensional array on c#

0 Answers0