No, it won't work and here's why. User 1 launches your application and changes the file so it can be USEd. Then User 2 double clicks on it in Windows Explorer and opens the file.

>Dear Experts.
>
>I copy following two procedures from a Foxbase prg. All of the DBF files work fine within Exe. But when someone try to open them by double clicking or even in Foxpro then a message appears "Not a dbf file".
>
>May be this is a good trick to avoid databaes files to open without exe.
>Is it possible to use this or such other procedure within Visual Foxpro.
>
>&& FUNCTION PROTECT
>

>PARAMETERS FN
>BUFFER=" "
>HANDLE=FOPEN(FN,2)
>IF HANDLE>-1
>   FREAD(HANDLE,@BUFFER,1)
>   FBYTE=ASC(BUFFER)
>   FSEEK(HANDLE,0,0)
>   IF FBYTE=3
>      FWRITE(HANDLE,CHR(26),1)
>   ENDIF
>   FCLOSE(HANDLE)
>ENDIF
>RETURN .T.
>

>
>* Function Unprotect
>

>PARAMETERS FN
>BUFFER=" "
>HANDLE=FOPEN(FN,2)
>IF HANDLE>-1
>   FREAD(HANDLE,@BUFFER,1)
>   FBYTE=ASC(BUFFER)
>   FSEEK(HANDLE,0,0)
>   IF FBYTE=26
>      FWRITE(HANDLE,CHR(03),1)
>   ENDIF
>   FCLOSE(HANDLE)
>ENDIF
>RETURN .T.
>