字符串（汉字、英文和数字混杂皆可）拼音首字母，用到微软的Microsoft Visual Studio International Pack的拼音功能(dll)

using Microsoft.International.Converters.PinYinConverter;

private string GetFirstPhoneticAlphabetOfChineseCharacters(string a)
        {
            string result = "";
            char[] ch = a.ToCharArray();
            foreach (char c in ch)
            {
                try
                {
                    ChineseChar chineseChar = new ChineseChar(c);
                    result += chineseChar.Pinyins[0].ToString().Substring(0, 1);
                }
                catch
                {                    
                    result += c.ToString();
                }
            }
            return result;
        }