Iterate through 2 dimensional array c#

Well, usualy when you want to iterate on a 2D array:

for(int col = 0; col < arr.GetLength(0); col++)
    for(int row = 0; row < arr.GetLength(1); row++)
        arr[col,row] =  /*something*/;

Arrays are always zero-based, so there's no point of trying to get something at -1 index.

string[,] arr = new string[2, 3];
        arr[0, 0] = "0,0";
        arr[0, 1] = "0,1";
        arr[0, 2] = "0,2";

        arr[1, 0] = "1,0";
        arr[1, 1] = "1,1";
        arr[1, 2] = "1,2";

        for (int i = 0; i < arr.GetLength(0); i++)
        {
            for (int j = 0; j < arr.GetLength(1); j++)
            {
                Response.Write(string.Format("{0}\t", arr[i, j]));
            }
            Response.Write("<br/>");
        }

If odds is a two-dimensional array, then its dimensions will be called 0 and 1. Trying to access dimension -1 will yield an IndexOutOfRangeException.

GetLength is zero-based. Try calling GetLength(0).

I see one or two problems depending on how you intend to use it:

First off, GetLength(ind dimension) returns length of specified dimension, starting from 0. In case of a two-dimensional array, correct indices would be 0 and 1.

The second problem is that you are doing <= instead of < for loop condition, which might also go out of bounds since last index is length-1 and not length.

StriplingWarrior and Gilad Naaman posted code examples so I'll skip that.

Accepted answer is correct and perfectly fine. I just wanted to mention another, perhaps more convenient way how to traverse Multidemensional arrays, by making use of IEnumerable interface. This approach is in my opinion more convenient than iterating using indeces, but there is slight overhead of creating the iterator and each step calling MoveNext() on the iterator, so it is a little bit slower.

Example of using IEnumerable from c# docs:

int[,] numbers2D = { { 9, 99 }, { 3, 33 }, { 5, 55 } };

foreach (int i in numbers2D)
{
    System.Console.Write($"{i} ");
}
// Output: 9 99 3 33 5 55

int[,,] array3D = new int[,,] { { { 1, 2, 3 }, { 4,   5,  6 } },
                        { { 7, 8, 9 }, { 10, 11, 12 } } };
foreach (int i in array3D)
{
    System.Console.Write($"{i} ");
}
// Output: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12

Note that jagged arrays surprisingly cannot be traversed using IEnumerable interface.

I followed the accepted answer but it throw exception in my code.

This is my way to iterate 2 dimension array using 2 foreach loop. I share for whom concerned.

int i = 0;
      
foreach (var innercell in cells)
{
    int j = 0;
    foreach (var item in innercell)
    {
       if (j == cell.Col && cell.Row == i)
       {
         item.TagName = cell.TagName;
         item.Text = cell.Text;
         exist = true;
         break;
        }
        j++;
     }
     i++;
}

The following code will iterate over the 2 Dimensional array named arr and will calculate the sum of all its elements.

int sum =0;
for (int i = 0; i < arr.Length; i++)
    {
        for (int j = 0; j < (arr[i]).Length; j++)
        {
            sum+=(arr[i][j]);
        }
     }