[No0000107]C#中 Excel列字母与数字的转换

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.Regularexpression_rs;

namespace Hooogle
{
    public static class ExcelConvert
    {
        #region - 由数字转换为Excel中的列字母 -

        public static int ToIndex(string columnName)
        {
            if (!Regex.IsMatch(columnName.ToUpper(), @"[A-Z]+")) { throw new Exception("invalid parameter"); }

            int index = ;
            char[] chars = columnName.ToUpper().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 ToName(int index)
        {
            if (index < ) { throw new Exception("invalid parameter"); }

            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());
        }
        #endregion
    }
}