以下是代碼，呵呵，比較簡單，主要是區分漢字和字母，不然一個全是字母，一個全是漢字的兩條記錄排列在一起時會比較難看，全字符的長度只有全漢字 的一半就顯示...號了
     public static string stringformat(string str,int n)
                {
                        ///
                        ///格式化字符串長度，超出部分顯示省略號,區分漢字跟字母。漢字2個字節，字母數字一個字節
                        ///
                        string temp=string.Empty;
                        if(System.Text.Encoding.Default.GetByteCount(str)<=n)//如果長度比需要的長度n小,返回原字符串
                        {
                                return str;
                        }
                        else
                        {
                                int t=0;
                                char[] q=str.ToCharArray();
                                for(int i=0;i<q.Length&&t<n;i++)
                                {
                                        if((int)q[i]>=0x4E00 && (int)q[i]<=0x9FA5)//是否漢字
                                        {
                                                temp+=q[i];
                                                t+=2;
                                        }
                                        else
                                        {
                                                temp+=q[i];
                                                t++;
                                        }
                                }
                                return (temp+"...");
                        }
               
                }