[Sinaloense]

Te pongo una UDF hecha en Pascal por mi hace unos meses, espero te sirva como ejemploo:


library aam;

{ Important note about DLL memory management: ShareMem must be the
first unit in your library's USES clause AND your project's (select
Project-View Source) USES clause if your DLL exports any procedures or
functions that pass strings as parameters or function results. This
applies to all strings passed to and from your DLL--even those that
are nested in records and classes. ShareMem is the interface unit to
the BORLNDMM.DLL shared memory manager, which must be deployed along
with your DLL. To avoid using BORLNDMM.DLL, pass string information
using PChar or ShortString parameters. }

uses
SysUtils, ib_util,
Classes;

function ftstr(v:real):string;stdcall
begin
result:=FormatFloat('#,##0.00',v);
end;

function ceros(var n:integer;var s:integer): PChar;stdcall;
var
i: Integer;
sz:string;
begin
sz:=IntToStr(n);
For i:=0 to s-(Length(sz)) do
sz:='0'+sz;
i := 0;
result := pchar(sz);
end;


function DoubleToStr(var nouble;var al:integer): PChar;stdcall;
var
i,j,k: Integer;
sz,temp:string;
begin
i := 0;
temp:='';
sz:=trim(FormatFloat('$#,##0.00',n));
j:=13-length(sz);
for k:=j downto 1 do
temp:=temp+' ';
temp:=temp+sz;
if al=1 then
result := pchar(temp)
else
result := pchar(sz);
end;

exports ceros,DoubleToStr;


{$R *.res}

begin
end.




-----------------------------------------------------------------------


Y se anexa a Firebird de la sig. forma:



DECLARE EXTERNAL FUNCTION CEROS
INTEGER,
INTEGER
RETURNS CSTRING(10)
ENTRY_POINT 'ceros' MODULE_NAME 'aam'




-------------------------------------------------------------


Y se usa:


Select ceros(mi_campo_numerico,1) from mi_tabla



Y debe regresar:
10.2 convierte a $10.20