Excel detected that XLS was solved by the sylk File

If this occurs during Excel import, the reason is:

 
A text file starting with "ID" or "id_xxxx" (XXXX is a text string ). The first record of the sylk file is recorded in id_number. When Excel identifies the text starting with a text file, it interprets it as a sylk file. Excel will try to convert the file from the sylk format, but it cannot, because there is no valid sylk after the "ID" CharacterCode. Because Excel cannot convert the file, you receive an error message.

Example:
 

 1     Public   Void  Import ()  2   {  3 Datatable dt = Getdata (); 4   Response. Clear ();  5 Response. addheader ( "  Content-Disposition  " , "  Attachment; filename =  " + Datetime. Now. tostring ( "  Yyyymmddhhmmssfff  " ) + "  . Xls  " );  6 Response. contentencoding = encoding. getencoding ( "  Gb2312  "  );  7 Response. contenttype = "  Application/MS-Excel  "  ;  8 Stringwriter Sw = New  Stringwriter ();  9 Arraylist list = New  Arraylist ();  10           String Connstr = ""  ;  11           For ( Int I = 0 ; I <DT. Columns. Count; I ++ )  12   {  13 Connstr = connstr + dt. Columns [I]. columnname +"  \ T  "  ;  14   List. Add (Dt. Columns [I]. columnname );  15   }  16 Connstr = connstr. substring ( 0 , Connstr. Length- 1  );  17   Sw. writeline (connstr );  18          For ( Int I = 0 ; I <DT. Rows. Count; I ++ )  19   {  20 Connstr = ""  ;  21               For ( Int J = 0 ; J <DT. Columns. Count; j ++ )  22  {  23 Connstr = connstr + dt. Rows [I] [list [J]. tostring ()]. tostring () + "  \ T  "  ;  24   }  25 Connstr = connstr. substring ( 0 , Connstr. Length- 1  );  26   Sw. writeline (connstr ); 27   }  28   Response. Write (SW. tostring ());  29   Response. Flush ();  30   Response. Close ();  31   }  32       Public  Datatable getdata ()  33   {  34 Datatable dt = New  Datatable ();  35 DT. Columns. Add ( "  Id_numeric  " , Typeof ( String  ));  36 DT. Columns. Add ( "  Productname  " , Typeof (String  ));  37 Datarow DR = DT. newrow ();  38 Dr [ "  Id_numeric  " ] = "  1  "  ;  39 Dr [ "  Productname  " ] ="  Sodium Chloride Injection  "  ;  40   DT. Rows. Add (DR );  41 Dr = DT. newrow ();  42 Dr [ "  Id_numeric  " ] = "  2  "  ; 43 Dr [ "  Productname  " ] = "  Potassium Chloride Injection  "  ;  44   DT. Rows. Add (DR );  45           Return  DT;  46   }  47       Protected  Void Button#click ( Object  Sender, eventargs E)  48   {  49   Import ();  50 }

Initial code

You can solve the problem by converting ID or id_numeric to lowercase letters:

Example:

 1       Public   Void  Import ()  2   { 3 Datatable dt = Getdata ();  4   Response. Clear ();  5 Response. addheader ( "  Content-Disposition  " , "  Attachment; filename =  " + Datetime. Now. tostring ( "  Yyyymmddhhmmssfff  " ) +"  . Xls  "  );  6 Response. contentencoding = encoding. getencoding ( "  Gb2312  "  );  7 Response. contenttype = "  Application/MS-Excel  "  ;  8 Stringwriter Sw =New  Stringwriter ();  9 Arraylist list = New  Arraylist ();  10           String Connstr = ""  ;  11           For ( Int I = 0 ; I <DT. Columns. Count; I ++ )  12  {  13 Connstr = connstr + dt. Columns [I]. columnname + "  \ T  "  ;  14   List. Add (Dt. Columns [I]. columnname );  15   }  16 Connstr = connstr. substring ( 0 , Connstr. Length- 1  ); 17   Sw. writeline (connstr );  18           For ( Int I = 0 ; I <DT. Rows. Count; I ++ )  19   {  20 Connstr = ""  ;  21               For ( Int J =0 ; J <DT. Columns. Count; j ++ )  22   {  23 Connstr = connstr + dt. Rows [I] [list [J]. tostring ()]. tostring () + "  \ T  "  ;  24   }  25 Connstr = connstr. substring ( 0 , Connstr. Length- 1 );  26   Sw. writeline (connstr );  27   }  28   Response. Write (SW. tostring ());  29   Response. Flush ();  30   Response. Close ();  31   }  32       Public  Datatable getdata () 33   {  34 Datatable dt = New  Datatable ();  35 DT. Columns. Add ( "  Id_numeric  " , Typeof ( String  ));  36 DT. Columns. Add ( "  Productname " , Typeof ( String  ));  37 Datarow DR = DT. newrow ();  38 Dr [ "  Id_numeric  " ] = "  1  "  ;  39 Dr ["  Productname  " ] = "  Sodium Chloride Injection  "  ;  40   DT. Rows. Add (DR );  41 Dr = DT. newrow ();  42 Dr [ "  Id_numeric  " ] = " 2  "  ;  43 Dr [ "  Productname  " ] = "  Potassium Chloride Injection  "  ;  44   DT. Rows. Add (DR );  45           Return  DT;  46  }  47       Protected   Void Button#click ( Object  Sender, eventargs E)  48   {  49   Import ();  50 }

Modified code