How to initialize objects inside two dimensional array?

Question

I got a two dimensional Array

BoardTile tiles[,];

and then in Init(Point size) I set its size:

tiles = new BoardTile[size.X, size.Y];

And how do I initialize all those elements because it does not use default BoardTile() constructor. It just assigns null.

foreach(BoardTile t in tiles) t = new BoardTile()

Does not work. And when I try to call

foreach(BoardTile t in tiles) t.anything()

I get NullReferenceException.

Use a for loop for each dimension. That's shown in all array tutorials. foreach is introduced for enumerating collections — Panagiotis Kanavos
– Panagiotis Kanavos, Commented Mar 13, 2019 at 11:23
Also that's not a dynamically sized array, the array size will not change after initialization. — SᴇM
– SᴇM, Commented Mar 13, 2019 at 11:28

Dmitrii Bychenko · Accepted Answer · 2019-03-13 11:35:03Z

5

You can try nested loops:

  for (int i = 0; i < titles.GetLength(0); ++i)
    for (int j = 0; j < titles.GetLength(1); ++j)
      titles[i, j] = new BoardTile();

Edit: if nested loops are too complex and unreadable, try switching to jagged arrays i.e. array of array - BoardTile tiles[][]; - from 2D one BoardTile tiles[,], e.g.

   // created and initialized jagged array
   BoardTile tiles[][] = Enumerable
     .Range(size.Y)                      // size.Y lines
     .Select(y => Enumerable             // each line is
        .Range(size.X)                   //   size.X items
        .Select(x => new BoardTile())    //   each of them is BoardTile()
        .ToArray())                      //   materialized as array
     .ToArray();                         // all arrays are array of array

edited Mar 13, 2019 at 11:35

answered Mar 13, 2019 at 11:23

Dmitrii Bychenko

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3 Comments

SkillGG Over a year ago

Is it the only way? I thought about this solution, but this looks for me like it could be done easier.

Dmitrii Bychenko Over a year ago

@SkillGG: unlike jagged arrays (array of array BoardTile[][]) multidimensional ones (BoardTile[,]) are not very handy.

SkillGG Over a year ago

Okay. Thank for your help. I guess I'm stuck with this ugly double-loop init.

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