As3 - Script Error on Arrays

Question

please inspect me coding:

function createRandomList():void
{
    var newlist:Array = [0,1,2];
    var curlist:Array = item[selectedlevel - 1] //selectedlevel = 1;
    var normal:int = curlist[0];
    var tempboo1:Boolean = false;
    var tempboo2:Boolean = false;
    var tempboo3:Boolean = false;
    while (curlist[0] + curlist[1] + curlist[2] > 0)
    {
        if (Number(curlist[0]) == 0 && tempboo1 == false)
        {
            newlist.splice(newlist.indexOf(0), 1);
            tempboo1 = true;
        }
        if (Number(curlist[1]) == 0 && tempboo2 == false)
        {
            newlist.splice(newlist.indexOf(1), 1);
            tempboo2 = true;
        }
        if (Number(curlist[2]) == 0 && tempboo3 == false)
        {
            newlist.splice(newlist.indexOf(2), 1);
            tempboo3 = true;
        }
    var temp:int = Math.floor(Math.random()*(newlist.length));
    curlist[temp] -=  1;
    generatedlist.push(Number(newlist[temp]));
        trace(item);
    }

    while (normal > 0)
    {
        var temp2:int = Math.floor(Math.random() * 3) + 1;
        generatednormal.push(Number(temp2));
        normal--;
    }
}

My item was [[5,0,0],[10,0,0]]; But after became [[0,0,0],[0,0,0]];

I just want to duplicate Array item to be a new variable curlist.

Every time it traces, returning item[0][0] decreasing 1, I only want to use curlist as a temp Array to calculate a new random Array based on item[0].

Ouput:

4,0,0,10,0,0
3,0,0,10,0,0
2,0,0,10,0,0
1,0,0,10,0,0
0,0,0,10,0,0

Is there any links between them, or is it my problem? Please help! If you need any more infoemation, please comment me!

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

Arrays are passed by reference, not value. That means when you modify an array through any property that points to it, the original array will be modified.

To make a duplicate, you can use .slice()

Returns a new array that consists of a range of elements from the original array, without modifying the original array. The returned array includes the startIndex element and all elements up to, but not including, the endIndex element.

If you don't pass any parameters, the new array is a duplicate (shallow clone) of the original array.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered May 21, 2013 at 10:27

Marty

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2 Comments

Daniel Cheung Over a year ago

your answer works, i'm sorry, but i preferred RafH 's answer.

Marty Over a year ago

@DanielCheung That's fine, just be cautious of overhead that isn't necessary. .slice() is specifically designed for duplicating an array.

Community · Accepted Answer · 2017-05-23 10:25:51Z

0

You can clone your arrays if you want to create a new reference.

function clone( source:Object ):* 
{ 
    var myBA:ByteArray = new ByteArray(); 
    myBA.writeObject( source ); 
    myBA.position = 0; 
    return( myBA.readObject() ); 
} 

var a:Array = [[0,0],[1,1]];
var b:Array = clone(a);

b[0] = [2,2];

trace(a)
trace(b)

Output

0,0,1,1
2,2,1,1

It works for any object, not only arrays. More infos here : AS3 - Clone an object

edited May 23, 2017 at 10:25

CommunityBot

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answered May 21, 2013 at 10:29

RafH

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2 Comments

Marty Over a year ago

For anyone stumbling upon this answer - be aware that this method is around 10-15x slower than using .slice().

Discipol Over a year ago

Your deep cloning methods falls very short when having no primitives in your array. But for numbers & such, this is a simple solution, indeed, albeit slow, as Marty mentioned.

Discipol · Accepted Answer · 2013-05-21 10:22:02Z

0

var array : Array = [ 1, 2, 3];
var array2 : Array = array.concnt();
array[ 0 ] = 4;
trace( array );// 1, 2, 3
trace( array 2);// 4, 2 ,3

So use .concat() to duplicate an array with primitives. If you have an arrays with arrays. Duplicate the children arrays, and put them into an empty one. If you have children of children arrays and so forth, make something recursive.

answered May 21, 2013 at 10:22

Discipol

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2 Comments

Daniel Cheung Over a year ago

your answer works, i'm sorry, but i preferred RafH 's answer.

Discipol Over a year ago

Sure, take care if you are adding complex objects like Sprite. RafH's method will either freeze your application and/or not work properly.

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