cast an object to multidimensional string array

Question

I have seen how to cast an object to a string array using the code below,

string[] arr = ((IEnumerable)paraArray).Cast<object>()
                             .Select(x => x.ToString())
                             .ToArray();

My question though is if paraArray is a object (but the data is a multidimensional array) how can I cast it to a multidimensional string array?

That code isn't casting anything as a string array. It's converting each object in a list into a string and then creating a new string array and populating it with those values. You seem to be under some serious misconceptions regarding what casting actually is and does. Casting something as a string array would look like this: var myArray = (string[]) myObject;. — jmcilhinney
– jmcilhinney, Commented Aug 11, 2016 at 7:20
yeh the paraArray is passed to the function as an object. The object though I know contains rows and columns of string and double data — mHelpMe
– mHelpMe, Commented Aug 11, 2016 at 7:22

Dmitrii Bychenko · Accepted Answer · 2016-08-11 07:26:41Z

5

You can't achieve this via ToArray. The best, IMHO, you can do is

  object[,] paraArray = new object[,] {
    {1, 2, 3 },
    {4, 5, 6 },
  };

  ...

  string[,] arr = new string[paraArray.GetLength(0), paraArray.GetLength(1)];

  for (int i = 0; i < arr.GetLength(0); ++i)
    for (int j = 0; j < arr.GetLength(1); ++j)
      arr[i, j] = paraArray[i, j].ToString();

2d arrays are not very convenient when working with Linq, that's why often jagged arrays (array of array) are preferable:

  object[][] paraArray = new object[][] {
    new object[] {1, 2, 3 },
    new object[] {4, 5, 6 },
  };

  ... 

  // Working with jagged array is much easier than with 2d one 
  string[][] arr = paraArray
    .Select(line => line
       .Select(item => item.ToString())
       .ToArray())
    .ToArray();

edited Aug 11, 2016 at 7:26

answered Aug 11, 2016 at 7:16

Dmitrii Bychenko

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4 Comments

mHelpMe Over a year ago

Oh its fine for it to be a jagged array. I will give that a go. If my paraArray is being passed as an object would I able to use the GetLength method or I guess I would have to do something to paraArray first?

downrep_nation Over a year ago

Object doesnt natively inherit a length method, you will have to cast it

Dmitrii Bychenko Over a year ago

@downrep_nation: I call arr.GetLength(...) on arr which is an array, not just object

downrep_nation Over a year ago

@DmitryBychenko thats fine, i was answering op's question

Community · Accepted Answer · 2017-05-23 10:28:40Z

3

Instead of using LINQ for this, you can use Array.Copy, as in this answer.

object[,] paraArray = new object[2, 2] { { "a", "b" }, { "c", "d" } };

string[,] stringArray = new string[paraArray.GetLength(0), paraArray.GetLength(1)];

for (int i = 0; i < paraArray.GetLength(0); ++i)
{
    Array.Copy(paraArray, i * paraArray.GetLength(1), stringArray, i * stringArray.GetLength(1), paraArray.GetLength(1));
}

edited May 23, 2017 at 10:28

CommunityBot

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answered Aug 11, 2016 at 7:20

Patrick Hofman

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