I am getting the following error in my code and I can't seem to understand why. Can anyone help me with it?

This is my current code. The line causing the error is marked in a comment near the end.

var rows : int = 4;
var cols : int = 4;
var totalCards : int = cols * rows;
var matchesNeedToWin : int = totalCards * 0.5; 
var matchesMade : int = 0;

var cardW : int = 100;
var cardH : int = 100;

var aCards : Array; 
var aGrid : Array;

// This Array will store the two cards that the player flipped
var aCardsFlipped : ArrayList; 

// To prevent player from clicking buttons when we don't want him to
var playerCanClick : boolean; 

var playerHasWon : boolean = false;     

class Card extends System.Object {
var isFaceUp : boolean = false;
var isMatched : boolean = false;
var img : String;

    function Card () {
        img = "robot";

function Start () {

    var i : int = 0;
    var j : int = 0;

    playerCanClick = true;
    aCards = new Array ();
    aGrid = new Array ();
    aCardsFlipped = new ArrayList ();

    for ( i = 0; i < rows; i++) {
        aGrid [i] = new Array ();

            for (j = 0; j < cols; cols++ ) {
            aGrid [i] [j] = new Card (); // <------ Error over here

function Update () {
    Debug.Log("Game Screen has loaded");

The error states as follows:

Error BCE0048: Type 'Object' does not support slicing. (BCE0048) (Assembly-UnityScript)

  • \$\begingroup\$ Please comment #pragma strict Hope this helps \$\endgroup\$
    – user35491
    Sep 26, 2013 at 12:27

2 Answers 2


Like Jonathan Hobbs said, I've made a few changes.
This is what I modified those code

var aCards:Array
var aGrid:Card[,]; //<-- change how you declare this variable to multidimensional arrays
var aCardsFlipped:ArrayList;

And change this in the Start function

function Start () {
    playerCanClick = true; 
    aCards = new Array();
    aGrid = new Card[rows,cols]; //<-- I instantiate it as rows*cols array
    aCardsFlipped = new ArrayList();
    for (var i=0;i<rows;i++)
        for (var j=0;j<cols;j++)
            aGrid[i,j] = new Card(); //<-- Then assign the value like this

Hope this help

  • 2
    \$\begingroup\$ I would upvote your answer if you actually made it clear what you changed. Others with the same problem (but different code) will come to this site for a solution, so a good answer would let them know what's going on, too, so they can fix it for themselves (since copying+pasting the code above would do nothing for them, and it contains no value to their situation unless they dive in and try to find out what you changed). \$\endgroup\$ Jun 26, 2012 at 21:34

Javascript doesn't support multidimensional arrays well, so either switch to storing an array of objects or switch to C# in order to use multidimensional arrays.

This advice came up in answers to this Unity question. Meanwhile, according to this other question, you can declare them like this:

var a : float[,];

Or in your case, I'm guessing the syntax would be this (with or without the new, I'm not sure):

aGrid = new Card[,];

So instead of your problematic line you'd have this:

aGrid[i,j] = new Card();

If you really do want to use a jagged array you need to use a workaround (according to that first link): use the Array.Add() method rather than directly setting the variable at each index.

  • \$\begingroup\$ +1 for a good answer that was probably used without acceptance. \$\endgroup\$
    – House
    Jun 14, 2012 at 14:02
  • \$\begingroup\$ well this answer omits a couple crucial facts (which I'm editing in) so vish may not have gotten this working \$\endgroup\$
    – jhocking
    Sep 26, 2013 at 12:52
  • \$\begingroup\$ @jhocking What were the omitted crucial facts? If it's the poor native support for multidimensional arrays, that's true - just not in Unity's version of it, which supports multidimensional arrays just fine. They're used right there in the post - that's native JavaScript code in Unity, if I understand correctly. \$\endgroup\$ Sep 26, 2013 at 13:09
  • \$\begingroup\$ oh I didn't notice the dates on the responses on those links; apparently this used to be an issue (as in a couple years ago) but it's since changed. I'm not going to edit the post back because I seem to be a little mistaken here, but maybe add a note that the information in the first link is dated so that can cause confusion \$\endgroup\$
    – jhocking
    Sep 26, 2013 at 16:30

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .