C# 截取字符串方法（包含中英混合）

 private string GetByteString(string center, int maxlen, string endStr)
         {
             string temp = center.Substring(, (center.Length < maxlen + ) ? center.Length : maxlen + );
             byte[] encodedBytes = System.Text.ASCIIEncoding.ASCII.GetBytes(temp);
             string outputStr = "";
             int count = ;
             for (int i = ; i < temp.Length; i++)
             {
                 if ((int)encodedBytes[i] == )
                     count += ;
                 else
                     count += ;

                 if (count <= maxlen - endStr.Length)
                     outputStr += temp.Substring(i, );
                 else if (count > maxlen)
                     break;
             }
             if (count <= maxlen)
             {
                 outputStr = temp;
                 endStr = "";
             }
             outputStr += endStr;
             return outputStr;
         }