asp.net 获取汉字首字母

/// <summary>
/// 获取一个简体中文字的拼音首字母
/// </summary>
/// <param name="cn">一个简体中文字</param>
/// <returns>拼音首字母</returns>
public string getSpell(string cnStr)
{
string en = "";
List<string> list = new List<string>();
if (cnStr.Length > 1)
{
for (int i = 0; i < cnStr.Length; i++)
{
list.Add(cnStr.Substring(i, 1));
}
}
foreach (string cn in list)
{
byte[] arrCN = Encoding.Default.GetBytes(cn);
if (arrCN.Length > 1)
{
int area = (short)arrCN[0];
int pos = (short)arrCN[1];
int code = (area << 8) + pos;
int[] areacode = { 45217, 45253, 45761, 46318, 46826, 47010, 47297, 47614, 48119, 48119, 49062, 49324, 49896, 50371, 50614, 50622, 50906, 51387, 51446, 52218, 52698, 52698, 52698, 52980, 53689, 54481 };
for (int i = 0; i < 26; i++)
{
int max = 55290;
if (i != 25) max = areacode[i + 1];
if (areacode[i] <= code && code < max)
{
en += Encoding.Default.GetString(new byte[] { (byte)(65 + i) });
}
}
}
else en += cn2;
}
return en;
}