Finding the position of an element in a two-dimensional array?

Question

Well a simple question here (maybe not a simple answer?)

Let's say I have a two-dimensional array

[0] [1] [2] [3] [4] [5] [6] [7] [8] 

Now suppose I want to get the position of number 6

I know that with a one-dimensional array I can use Array.indexOf (), but what would my options be with 2-dimensional arrays?

Thanks!

Answer 1

I would say something like this:

 public static Tuple<int, int> CoordinatesOf<T>(this T[,] matrix, T value) { int w = matrix.GetLength(0); // width int h = matrix.GetLength(1); // height for (int x = 0; x < w; ++x) { for (int y = 0; y < h; ++y) { if (matrix[x, y].Equals(value)) return Tuple.Create(x, y); } } return Tuple.Create(-1, -1); } 

Answer 2

Here is a method that should find an index in an array with an arbitrary rank.

... Added a range of upper / lower bounds for the rank

 public static class Tools { public static int[] FindIndex(this Array haystack, object needle) { if (haystack.Rank == 1) return new[] { Array.IndexOf(haystack, needle) }; var found = haystack.OfType<object>() .Select((v, i) => new { v, i }) .FirstOrDefault(s => svEquals(needle)); if (found == null) throw new Exception("needle not found in set"); var indexes = new int[haystack.Rank]; var last = found.i; var lastLength = Enumerable.Range(0, haystack.Rank) .Aggregate(1, (a, v) => a * haystack.GetLength(v)); for (var rank =0; rank < haystack.Rank; rank++) { lastLength = lastLength / haystack.GetLength(rank); var value = last / lastLength; last -= value * lastLength; var index = value + haystack.GetLowerBound(rank); if (index > haystack.GetUpperBound(rank)) throw new IndexOutOfRangeException(); indexes[rank] = index; } return indexes; } }