ASP.NET截取字串

#region 格式化字串,取字串前 strLength 位，其他的用...代替.計算字串長度。漢字兩個位元組，字母一個位元組FormatString(string str,int len)

              /// <summary>

              /// 格式化字串,取字串前 strLength 位，其他的用...代替.計算字串長度。漢字兩個位元組，字母一個位元組

              /// </summary>

              /// <param name="str">字串</param>

              /// <param name="strLength">字串長度</param>

              /// <returns></returns>

              public static string FormatStr(string str,int len)

              {                    

                     ASCIIEncoding ascii = new ASCIIEncoding();

                     int tempLen=0;

                     string tempString="";

                     byte[] s = ascii.GetBytes(str);

                     for(int i=0;i<s.Length;i++)

                     {

                            if((int)s[i]==63)

                            {

                                   tempLen+=2;

                            }

                            else

                            {

                                   tempLen+=1;

                            }

                            try

                            {

                                   tempString+=str.Substring(i,1);

                            }

                            catch

                            {

                                   break;

                            }

                            if(tempLen>len)

                                   break;

                     }

                     //如果截過則加上半個省略符號

                     byte[] mybyte=System.Text.Encoding.Default.GetBytes(str);

                     if(mybyte.Length>len)

                            tempString+="...";

                     tempString=tempString.Replace(" ","  ");

                     tempString=tempString.Replace("<","<");

                     tempString=tempString.Replace(">",">");

                     tempString=tempString.Replace('\n'.ToString(),"<br>");

                     return tempString;

              }

              #endregion