Custom String Sorting C#

Custom String Sorting C#

public static string[] customSort(string[] unsortedArray)
{
  var onlyNumber = new List<string>();
  var onlyAlpha = new List<string>();
  var startAlpha = new List<string>();
  var startNum = new List<string>();

  // Fisrt we will sort the array using the inbuild array sort function
  Array.Sort(unsortedArray);

  // Check for 
  foreach (var value in unsortedArray)
  {
    // Only Numbers
    if (Regex.IsMatch(value, @"^\d+$"))
    {
      onlyNumber.Add(value);
    }
    // Only Alpha
    else if (Regex.IsMatch(value, @"^[a-zA-Z]+$"))
    {
      onlyAlpha.Add(value);
    }
    // Starts With Number
    else if (Regex.IsMatch(value, @"^\d"))
    {
      startNum.Add(value);
    }
    else
    {
      startAlpha.Add(value);
    }
  }
  // Priscy remove this if not requried.
  //var finalList = new List<string>();
  //finalList = onlyAlpha.Concat(startAlpha).ToList().Concat(startNum).ToList().Concat(onlyNumber).ToList();
  string[] sortedList = onlyAlpha.Concat(startAlpha).ToList().Concat(startNum).ToList().Concat(onlyNumber).ToList().ToArray();
  return sortedList;
}