Determines the file extension from a full filename.

        public static string GetFileType(string FilePath)
        {
            List<int> PeriodPostions = new List<int>();
            int ExtensionStart = 0;
            for (int iii = 0; iii < FilePath.Length; iii++)
            {
                if (FilePath[iii] == '.')
                {
                    PeriodPostions.Add(iii);
                }
            }
            ExtensionStart = PeriodPostions.Last();
            return FilePath.Substring(ExtensionStart);
        }