Excel列字母和数字的转换

网上看的，收藏备用

//用于excel表格中列号字转成数字，返回的列号索引从1开始

        public  int ToIndex(string columnName)

        {

            if (!Regex.IsMatch(columnName.ToUpper(), @"[A-Z]+"))

                throw new Exception("Invalid parameter");

            int index = 0;

            char[] chars = columnName.ToUpper().ToCharArray();

            for (int i = 0; i < chars.Length; i++)

            {

                index += ((int)chars[i] - (int)'A' + 1) * (int)Math.Pow(26, chars.Length - i - 1);

            }

            return index;

        }

 //用于将数字转成excel表格中列号字母，返回的列号索引从A开始，从A对应1开始

        public string ToName(int index)

        {

            if (index <= 0)

                throw new Exception("invaild parameter");

            

            index--;

            List<string> chars = new List<string>();

            do

            {

               if (chars.Count > 0)

                   index--;

                chars.Insert(0, ((char)(index % 26 + (int)'A' )).ToString());

                index = (int)((index - index % 26) / 26);

            } while (index > 0);

            

            return String.Join(string.Empty, chars.ToArray());

        }