Flatten Array C#

gistfile1.txt

static string Flatten(string array)
  {
      string result;  //return string
      try
      {
          bool previousWasNumber = false; //chech for numbers greater than 9
          result = "[";   //starting the array
          foreach (char c in array.ToCharArray())
          {
              int check = (int)c;     //check character
              if (!(check == 91 || check == 44 || check == 93)) // check if not [ , ]
              {
                  result += c;  // add the int to new array
                  previousWasNumber = true;
              }
              else
              {
                  if (previousWasNumber) result += ",";
                  previousWasNumber = false;
              }
          }
          result = result.Remove(result.Length - 1); //Remove last comma ,
          result += "]";  // end the array
          return result;
      }
      catch (Exception)
      {
          return "Not well formated array";   //Can include a lot of checks
      }

  }