Count a Char Number of Times in a String

C# Code

public ActionResult GetRepeatedCharactorCount(string enterdString)
{
string inputString = enterdString;
       List<string> resultStringList = new List<string>();
       char[] chrs = inputString.ToCharArray();
       for (int i = 0; i < chrsList.Length; i++)
       {
        int j = 0, count = 0;
              while ((j = inputString.IndexOf(chrsList[i], j)) != -1)
              {
                count++;
                        j++;
              }
              var outputting = string.Format("{0} Number of times repeat : {1} in                   {2}", chrsList[i], count, inputString);
              if (resultStringList.IndexOf(outputString) == -1)
              {
                resultStringList.Add(outputString);
              }
       }
       return Json(new { result = resultStringList}, JsonRequestBehavior.AllowGet);
}