Excel列A、B、C、D----与列序号的转换

   public static class ExcelConvert
     {
         public static int ToExcelIndex(this string columnName)
         {
             if (!Regex.IsMatch(columnName.ToUpper(), @"[A-Z]+"))
                 throw new Exception("错误参数");

             int index = ;
             char[] chars = columnName.ToUpper().Trim().ToCharArray();
             for(int i = ; i < chars.Length; i++)
             {
                 index += ((int)chars[i] - (int)'A' + ) * (int)Math.Pow(, chars.Length - i - );
             }
             return index - ;
         }

         public static string ToExcelName(this int index)
         {
             if(index<)
                 throw new Exception("错误参数");

             List<string> chars = new List<string>();
             do
             {
                 if (chars.Count > )
                     index--;
                 chars.Insert(, ((char)(index %  + (int)'A')).ToString());
                 index = (int)((index - index % ) / );
             } while (index > );
             return String.Join(string.Empty, chars.ToArray());
         }
     }

起始下标为0，即A＝0，B＝1......