C# 截取字符串，区分中英文情况

 public static string SubstringByCN(string strInput, int begin, int length)
         {
             if (!Regex.IsMatch(strInput, "[\u4E00-\u9FA5\uF900-\uFA2D]", RegexOptions.IgnoreCase))
             {
                 if (strInput.Length < length)
                     return strInput;
                 else
                     return strInput.Substring(, length);
             }
             else
             {
                 string checkstr = Regex.Replace(strInput, "[\u4E00-\u9FA5\uF900-\uFA2D]", "**", RegexOptions.IgnoreCase);
                 if (checkstr.Length < length)
                     return strInput;
                 else
                 {
                     string strOut = "";
                     int strLength = ;
                     for (int i = ; i < strInput.Length; i++)
                     {
                         if (strLength >= length)
                             break;
                         strOut += strInput.Substring(i, );
                         if (!Regex.IsMatch(strInput.Substring(i, ), "[\u4E00-\u9FA5\uF900-\uFA2D]", RegexOptions.IgnoreCase))
                             strLength += ;
                         else
                             strLength += ;
                     }
                     return strOut;
                 }
             }
         }