MarkovText.Markov.cleanupString C# (CSharp) Method

        private string cleanupString(string input)
        {
            StringBuilder sb = new StringBuilder();
            foreach (char c in input)
            {
                if ((c >= 20) && (c <= 126))
                    sb.Append(c.ToString());
                else sb.Append("-");
            }
            return sb.ToString();
        }