数字转成字母的方法

一个将数字转成字母的方法

        private static string Num_to_letter(int value)
        {
            //此处判断输入的是否是正整数数字
            if (Regex.IsMatch(value.ToString(), "^\d+$"))
            {
                int remainder = value % 26;
                //remainder = (remainder == 0) ? 26 : remainder;
                int front = (value - remainder) / 26;
                if (front == 0)
                {
                    return Level[remainder];
                }
                else if (front < 26)
                {
                    return Level[front - 1] + Level[remainder];
                }
                else
                {
                    return Num_to_letter(front) + Level[remainder];
                }
            }
            else
            {
                return string.Empty;
            }

        }