C# - Encode To ASCII - Buchstaben in Ascii-Werte umwandeln

public static string EncodeToAscii(string input)
{
   StringBuilder output = new StringBuilder(string.Empty);
   if (!string.IsNullOrEmpty(input))
   {
      for (int i = 0; i < input.Length; i++)
         output.AppendFormat("&#{0};", 
            Encoding.ASCII.GetBytes(input.Substring(i, 1))[0]);
   }
   return output.ToString();
}