ntToLetter将Excel列的整数索引值转换为字符索引值

/// <summary>
  /// 将Excel列的整数索引值转换为字符索引值
  /// </summary>
  /// <param name="n"></param>
  /// <returns></returns>
  public string IntToLetter(int n)
  {
   if(n > 256)
    throw new Exception("索引超出范围，Excel的列索引不能超过256！");
    
   int i = Convert.ToInt32(n / 26);
   int j = n % 26;

   char c1 = Convert.ToChar( i + 64 );
   char c2 = Convert.ToChar( j + 64 );

   if(n > 26)
    return c1.ToString() + c2.ToString();
   else if(n == 26)
    return "Z";
   else
    return c2.ToString();
  }