C# multidimensional array in line

Question

I'm writing a class to hold a three-dimensional array as a one-dimensional.

I have a bug in the code: all writen elements when the size of the array 1x1 (xz) are null.

Tell me where is the mistake and tell me what libraries already for this?

public class Arr3D<T> {

private T[] arr;
private Vector3 min, max;
private Vector3 size;

public Arr3D() 
{
    arr = new T[0];
}

public void AddOrReplace(T obj, Vector3 pos) 
{
    Vector3 newMin = Vector3.Min(min, pos); // ( Min(x1,x2), Min(y1,y2), ...
    Vector3 newMax = Vector3.Max(max, pos+Vector3.one); // +(1,1,1)

    if(newMin != min || newMax != max) 
    {
        Resize(newMin, newMax);
    }

    Set(obj, pos);
}

public void Set(T obj, Vector3 pos) 
{
    Set(obj, pos.x, pos.y, pos.z);
}

public void Set(T obj, int x, int y, int z) 
{
    arr[ (y-min.y)*size.x*size.y  +  (z-min.z)*size.x + (x-min.x) ] = obj;
}

private void Resize(Vector3 newMin, Vector3 newMax) 
{
    Vector3 oldMin = min;
    Vector3 oldMax = max;
    T[] oldList = arr;
    Vector3 oldSize = size;

    min = newMin;
    max = newMax;
    size = newMax - newMin;
    arr = new T[size.z*size.y*size.x];

    for(int x=oldMin.x; x<oldMax.x; x++) 
    {
        for(int y=oldMin.y; y<oldMax.y; y++) 
        {
            for(int z=oldMin.z; z<oldMax.z; z++) 
            {
                T val = oldList[(y-oldMin.y)*oldSize.x*oldSize.y  +  (z-oldMin.z)*oldSize.x + (x-oldMin.x)];
                Set(val, x, y, z);
            }
        }
    }

}

public T Get(int x, int y, int z) 
{
    return arr[(y-min.y)*size.x*size.y  +  (z-min.z)*size.x + (x-min.x)];
}
}

if oldList references arr and then you do a "new" on arr...oldList will also be empty — Mauricio Gracia Gutierrez
– Mauricio Gracia Gutierrez, Commented Dec 6, 2013 at 17:25

Mauricio Gracia Gutierrez · Accepted Answer · 2013-12-06 16:22:12Z

1

In the Resize method Instead of

T[] oldList = arr;

You should COPY the values of the arr(ay) otherwise you are keeping a reference to arr

T[] oldList ;

Array.Copy(arr,oldList,arr.Length) ;

For more details see Array.Copy method

edited Dec 6, 2013 at 16:22

answered Dec 6, 2013 at 16:04

Mauricio Gracia Gutierrez

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7 Comments

user1164554 Over a year ago

It will not work. One-dimensional array stores a three-dimensional. The elements are arranged like a dotted line. That is if we increase X by one, the new elements will not be the end of the array, and in the middle.

Mauricio Gracia Gutierrez Over a year ago

@user1164554 but the important idea is that you need to create copies of each of the values because if you keep a reference to arr and then call a "new" on arr you are going to end up with null values

Mauricio Gracia Gutierrez Over a year ago

@user1164554 you are asking about your mistake on null values, not about how to implemente 3 dimensional arrays in one-dimensional array

user1164554 Over a year ago

To be honest, until I see no reason to create new instances of objects and create extra garbage collector calls. Yes, transmitted links, but what's the problem?

Mauricio Gracia Gutierrez Over a year ago

@user1164554 then feel free to try your own aproach and solution

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