[Gambas-user] How to verify a date like dd/mm/yyyy?

[Benoit Minisini]

On vendredi 21 mars 2008, Richard wrote:
> On Friday 21 March 2008 14:44:51 Richard wrote:
> > On Friday 21 March 2008 12:57:04 Richard wrote:
> > > On Friday 21 March 2008 07:51:48 andy2 wrote:
> > > > in Php i found the following script. My problem is to replicate the
> > > > ereg function.
> > > >
> > > > FUNCTION ControlloData($data){
> > > >   If(!ereg("^[0-9]{2}/[0-9]{2}/[0-9]{4}$", $data)){
> > > >     RETURN FALSE;
> > > >   } ELSE {
> > > >     $arrayData = explode("/", $data);
> > > >     $Giorno = $arrayData[0];
> > > >     $Mese = $arrayData[1];
> > > >     $Anno = $arrayData[2];
> > > >     If(!checkdate($Mese, $Giorno, $Anno)){
> > > >       RETURN FALSE;
> > > >     } ELSE {
> > > >       RETURN TRUE;
> > > >     }
> > > >   }
> > > > }
> > > >
> > > > ---------------------------------------------------------------------
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> > > > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> > > > _______________________________________________
> > > > Gambas-user mailing list
> > > > Gambas-user at lists.sourceforge.net
> > > > https://lists.sourceforge.net/lists/listinfo/gambas-user
> > >
> > > You could also do something similar to the PHP code:
> > >
> > > PUBLIC FUNCTION is_date(data AS String) AS Boolean
> > > DIM aDateElements AS String[]
> > > DIM iDay AS Integer
> > > DIM iMth AS Integer
> > > DIM iYear AS Integer
> > >
> > >     IF NOT (data LIKE "[0-9][0-9]/[0-9][0-9]/[0-9][0-9][0-9][0-9]")
> > > THEN RETURN FALSE
> > >     ELSE
> > >         aDateElements = Split(data, "/")
> > >         iDay = aDateElements[0]
> > >         iMth = aDateElements[1]
> > >         iYear = aDateElements[2]
> > >         TRY RETURN IsDate(Date(iYear, iMth, iDay))
> > >         IF ERROR THEN RETURN FALSE
> > >     ENDIF
> > >
> > > END
> > >
> > > The Gambas LIKE operator is just as weak as the VB one and the mask I
> > > have shown will only check for digits. It will accept digits which do
> > > not make up a date (eg 72/33/1234); this is the same behaviour as your
> > > PHP regular expression.
> > >
> > >
> > > -----------------------------------------------------------------------
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> > > Defy all challenges. Microsoft(R) Visual Studio 2008.
> > > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> > > _______________________________________________
> > > Gambas-user mailing list
> > > Gambas-user at lists.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/gambas-user
> >
> > I suppose, in deference to the peculiar requirements of our northern
> > trans-atlantic brethren I should have taken more care in the example to
> > make it locale-aware.
> >
> > The trick, which I found when looking at the ValueBox code, is to
> > construct a localised version of the YYYY MM DD format string for a
> > gb.ShortDate. When we are extracting day and month from the array of date
> > element values we must know which one is the day and which the month.
> >
> > Benoit did it something like this:
> >
> >   sDateFormat = Format(Date(3333, 11, 22), gb.ShortDate)
> >
> > so now the month is represented by 11 and the day by 22. All we need to
> > do is check what the first two digits represent by looking at our date
> > format variable before we fetch values from the array.
> >
> > PUBLIC FUNCTION is_date(data AS String) AS Boolean
> > DIM aDateElements AS String[]
> > DIM iDay AS Integer
> > DIM iMth AS Integer
> > DIM iYear AS Integer
> > DIM $sDateFormat AS String
> >
> >     sDateFormat = Format(Date(3333, 11, 22), gb.ShortDate)
> >
> >     IF NOT (data LIKE "[0-9][0-9]/[0-9][0-9]/[0-9][0-9][0-9][0-9]") THEN
> >         RETURN FALSE
> >     ELSE
> >         aDateElements = Split(data, "/")
> >         iDay =
> > IIF(LEFT(sDateFormat,2)="22",aDateElements[0],aDateElements[1]) iMth =
> > IIF(LEFT(sDateFormat,2)="11",aDateElements[0],aDateElements[1]) iYear =
> > aDateElements[2]
> >         TRY RETURN IsDate(Date(iYear, iMth, iDay))
> >         IF ERROR THEN RETURN FALSE
> >     ENDIF
> >
> > END
> >
> > -------------------------------------------------------------------------
> > This SF.net email is sponsored by: Microsoft
> > Defy all challenges. Microsoft(R) Visual Studio 2008.
> > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> > _______________________________________________
> > Gambas-user mailing list
> > Gambas-user at lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/gambas-user
>
> One more attempt to get it right...
>
> I overlooked the assumption about the date format in the LIKE expression
> and the possibility to tighten up the comparison mask to make it a little
> more robust (not much).
>
> PUBLIC FUNCTION is_date(data AS String) AS Boolean
> DIM aDateElements AS String[]
> DIM iDay AS Integer
> DIM iMth AS Integer
> DIM iYear AS Integer
> DIM sDateFormat AS String
> DIM sMask AS String
>
>     sDateFormat = Format(Date(3333, 11, 22), gb.ShortDate)
>
>     IF LEFT(sDateFormat,2)="22" THEN
> 	sMask = "[0-3][0-9]/[0-1][0-9]/[0-9][0-9][0-9][0-9]"
>     ELSE
> 	sMask = "[0-1][0-9]/[0-3][0-9]/[0-9][0-9][0-9][0-9]"
>     ENDIF
>
>     IF NOT (data LIKE sMask) THEN
>         RETURN FALSE
>     ELSE
>         aDateElements = Split(data, "/")
>         iDay =
> IIF(LEFT(sDateFormat,2)="22",aDateElements[0],aDateElements[1]) iMth
> =IIF(LEFT(sDateFormat,2)="11",aDateElements[0],aDateElements[1]) iYear =
> aDateElements[2]
>         TRY RETURN IsDate(Date(iYear, iMth, iDay))
>         IF ERROR THEN RETURN FALSE
>     ENDIF
>
> END
>
>
> Richard
>

RETURN IsDate(Val(data)) is not complex enough? :-)

-- 
Benoit Minisini