UDF's input parameters are always passed by reference,
so the correct declaration is
Year: PInteger
and you should check whether Year is assigned (i.e. not nil).
(Current FB versions always pass valid pointer, but it can change
in the future)

This should work too (but can cause problems in future with nil pointer)
var Year: Integer

Ivan

----- Original Message -----
From: "Rick Roen" <rick@...>
To: <firebird-support@yahoogroups.com>
Sent: Tuesday, August 23, 2005 12:06 PM
Subject: [firebird-support] UDF for formatting dates/times


Firebird 1.5
Delphi 7 Pro

I'm confused about why my UDF works when I declare like this:

function fbFormatDateTime( FormatStr: PChar; var Year, Month, Day,
Hour, Min: Integer ): PChar; cdecl; export;

____________________

and does not work (disconnects from FB server upon execution) when
declared like this:

function fbFormatDateTime( FormatStr: PChar; Year, Month, Day, Hour,
Min: Integer ): PChar; cdecl; export;

_______________

The difference is in the "var" declaration before the year, month
etc.

BTW, I am just looking to format dates and times from within a SP
and could not find any other appropriate UDF in the free UDF
libraries. Is there something better available?

Also, I assume since I am using PChars and CStrings that I do not
need further memory freeing - is that correct?

Thanks,

Rick

Here is the full declaration in FB:

DECLARE EXTERNAL FUNCTION F_FORMAT_DATETIME
CSTRING(30),
INTEGER,
INTEGER,
INTEGER,
INTEGER,
INTEGER
RETURNS CSTRING(60)
ENTRY_POINT 'fbFormatDateTime' MODULE_NAME 'Primavera_UDF';

And here is the full Delphi UDF declaration:

function fbFormatDateTime( FormatStr: PChar; var Year, Month, Day,
Hour, Min: Integer ): PChar; cdecl; export;
var
Str: String;
begin
if not ( ( (Year>=1990) and (Year<=2100) ) and
( (Month>=1) and (Month<=12) ) and
( (Day>=1) and (Day<=31) ) and
( (Hour>=0) and (Hour<=23) ) and
( (Min>=0) and (Min<=60) ) ) then begin
Result := PChar( 'date/time error' );
Exit;
end;

Str := FormatDateTime( FormatStr, EncodeDateTime( Year, Month,
Day, Hour, Min, 0, 0 ) );
Result := PChar( Str );
end;