数字转换成字母帮助类

c# 实现excel（导出导入）非常实用的将数字转换成字母

   

/// <summary>
/// 需要转换的行或者列
/// </summary>
/// <param name="index"></param>
/// <returns></returns>
private static string nunbertochar(int index)
{

index = index - 1;
if (index < 0) { throw new exception("invalid parameter"); }

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());

}