public string lengadd(string stringa, string stringb, int count, int mode)  //以stringa的长度,未到count的长度则增加stringb,mode属性0是增加前面,1是增加后面

         {

             int stringaa = System.Text.Encoding.Default.GetBytes(stringa).Length;

             if (mode == )

             {

                 for (int i = ; i <= (count - stringaa); i++)

                 {

                     stringa = stringb + stringa;

                 }

             }

             else

             {

                 for (int i = ; i <= (count - stringaa); i++)

                 {

                     stringa = stringa + stringb;

                 }

             }

             return stringa;

         }