C#•17mo ago

❔ Offset property for array

Suppose I have an array: public int[,] paddedArray = new int[width + 6, height + 6]; I want to make a property that accesses values offset, to get something like unpaddedArray[x,y]: get gives paddedArray[x+3,y+3], and set will set paddedArray[x+3,y+3]; Would anyone know how to define this?

4 Replies

Loup&SnoopOP•17mo ago

I would like to do this in a really lightweight way, because the alternative is just to put a const everywhere, and that would just be obnoxious I could do something like :

private int[,] paddedIntGrid;
    public int GetInt(int x, int y) { return paddedIntGrid[x + PADDING, y + PADDING]; }
    public void SetInt(int x, int y, int myInt) { paddedIntGrid[x + PADDING, y + PADDING] = myInt; }

private int[,] paddedIntGrid;
    public int GetInt(int x, int y) { return paddedIntGrid[x + PADDING, y + PADDING]; }
    public void SetInt(int x, int y, int myInt) { paddedIntGrid[x + PADDING, y + PADDING] = myInt; }

But I'd like to know if there is a simpler way to make the syntax more like just accessing the array itself.

Vi Ness•17mo ago

You can use indexers to make something like this

internal class PaddedMatrix
{
    private int[,] _matrix;
    private int _padding;
    private int _halfPad;

    public PaddedMatrix(int size, int padding)
    {
        _padding = padding;
        _halfPad = _padding / 2;
        _matrix = new int[size+padding, size+padding];
    }

    public int this[int x, int y]
    {
        get => _matrix[x + _halfPad, y + _halfPad];
        set => _matrix[x + _halfPad, y + _halfPad] = value;
    }
}

internal class PaddedMatrix
{
    private int[,] _matrix;
    private int _padding;
    private int _halfPad;

    public PaddedMatrix(int size, int padding)
    {
        _padding = padding;
        _halfPad = _padding / 2;
        _matrix = new int[size+padding, size+padding];
    }

    public int this[int x, int y]
    {
        get => _matrix[x + _halfPad, y + _halfPad];
        set => _matrix[x + _halfPad, y + _halfPad] = value;
    }
}

https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/indexers/using-indexers

Using Indexers - C# Programming Guide

Learn how to declare and use an indexer for a class, struct, or interface in C#. This article includes example code.

Loup&SnoopOP•17mo ago

thank you. that is useful I tried to avoid a custom mini class, but I think it is worth it

Accord•17mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Offset property for array