equivalent for BYVAL %NULL?

[Egbert Zijlema]

Semen,

Thank you. In the meantime I found out, that using BYCOPY also works.
If you want to see an example then download my recently posted "get certain weekday from month" routine.

Regards,
Egbert

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[This message has been edited by Egbert Zijlema (edited July 06, 2000).]

[Semen Matusovski]

Egbert --
You can do something like this

   #Compile Exe
   #Register None
   #Dim All
   #Include "Win32Api.Inc"
   
   Function MakeDate(sFormat As String) As String
      Local szText As Asciiz * 255, FormatAddr As Dword, Flags As Dword
      If sFormat = "SHORTDATE" Then Flags = %DATE_SHORTDATE: FormatAddr = 0 Else _
      If sFormat = "LONGDATE" Then Flags = %DATE_LONGDATE: FormatAddr = 0 Else _
                                   Flags = 0: FormatAddr = StrPtr(sFormat)
      GetDateFormat %LOCALE_USER_DEFAULT, Flags, ByVal %Null, ByVal FormatAddr, szText, SizeOf(szText)
      Function = szText
   End Function
   
   Function PbMain
      MsgBox "ShortDate is " + MakeDate ("SHORTDATE")
      MsgBox "LongDate is " + MakeDate ("LONGDATE")
      MsgBox "Custom format is " + MakeDate("dddd dd/MM/yyyy")
   End Function

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[Egbert Zijlema]

Hello folks,

I've encountered a problem with GetDateFormat. In WIN32API.INC this API is declared as follows:

DECLARE FUNCTION GetDateFormat LIB "KERNEL32.DLL" _
          ALIAS "GetDateFormatA" (BYVAL Locale AS LONG, _
                                  BYVAL dwFlags AS LONG, _
                                  lpDate AS SYSTEMTIME, _
                                  lpFormat AS ASCIIZ, _
                                  lpDateStr AS ASCIIZ, _
                                  BYVAL cchDate AS LONG) AS LONG

You can use this in 2 ways. Either you pass %DATE_LONGDATE (or shortdate) through dwFlags and BYVAL %NULL through lpFormat, or you pass a special format (such as "MMMM d") through lpFormat, while dwFlags is zero.

First strange thing: lpFormat is declared as a null-terminated string, but in case you want to leave it empty, BYVAL %NULL, which is a numeric!, is the correct param. By what can you replace this, eventually? I want to build a FUNCTION that uses this API, but in such a way that it passes the correct variables through dwFlags or lpFormat, depending of the content of a param passed.
This is the idea:

FUNCTION MakeDate(sFormat AS STRING) AS STRING
  LOCAL lFormat AS LONG, st AS SYSTEMTIME, szText AS ASCIIZ * 255
 
  lFormat = VAL(sFormat)
  IF lFormat = 1 OR lFormat = 2 THEN sFormat = xxxx [here I need a valid replacement for BYVAL %NULL]   
  GetDateFormat %LOCALE_USER_DEFAULT, lFormat, st, sFormat, szText, SIZEOF(szText)  
  FUNCTION = szText
END FUNCTION

I tried several sorts of string operands, but nothing worked. The only thing I can get working is an IF...ELSE structure with 2 complete API-calls, but that's not what I want. I just want to alter the vars and then use the same API-call for both situations.

Any idea? Thanks in advance.
Regards,
Egbert

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[This message has been edited by Egbert Zijlema (edited July 04, 2000).]