DIA DA SEMANA SEM WEEKDAY

' WEEKDAY$(3.0) 
' WEEKDAY$ function returns the name of the day of a week 
'(abbreviated to three characters) for the specified date.
' DECLARE FUNCTION WEEKDAY$(Spec.Date$)
' Parameter 
'----------------------------------------------------------------
'    Spec.Date$  - Specified date in the form of MM-DD-YY 
'                  or MM-DD-CCYY (should be a valid date 
'                  in Gregorian calendar)
--------------------------------------------------------------------
' Examples 
'    WEEKDAY$(""          )="Fri"  - Today 03-08-2002
'    WEEKDAY$("*1-01-1996")="***"
'    WEEKDAY$("12-31-1996")="Tue"
'    WEEKDAY$("01-01-1997")="Wed"
'    WEEKDAY$("12-31-1997")="Wed"
'    WEEKDAY$("01-01-1998")="Thu"
'    WEEKDAY$("12-31-1998")="Thu"
'    WEEKDAY$("12-31-04"  )="Fri"

     DECLARE FUNCTION VALDGRE%(Spec.Date$)
     DefInt A-Z  ' All defaulted variables are integer
[c]     FUNCTION WEEKDAY$(Spec.Date$) PUBLIC

     If (Len(Spec.Date$) = 0) Then
        DT$ = Date$
     ElseIf (VALDGRE%(Spec.Date$)) Then
        DT$ = Spec.Date$
     Else
        WEEKDAY$ = "***"
        Exit Function
     End If

     Month = Val(Left$(DT$, 2))
     Day = Val(Mid$(DT$, 4, 2))

     If (Len(DT$) = 8) Then
        Year = Val(Mid$(Date$, 7, 2) + Right$(DT$, 2)) 
     Else
        Year = Val(Right$(DT$, 4))
     End If

     If (Month < 3) Then
        Month = Month + 12
        Year = Year - 1
     End If

     Day.Index = (Day + Int((13 * Month - 27) / 5) + Year + Int(Year / 4) - Int(Year / 100) + Int(Year / 400)) Mod 7

     WEEKDAY$ = Mid$("SunMonTueWedThuFriSat", 3 * Day.Index + 1, 3)
End Function