asked on

passing line number to a DLL

I have an app which reads strings from a file processes it in a DLL before showing the output. The problem I have is that the information is kept over to lines and I need the DLL to recognise which line it is reading from.

So the DLL is as follows
---------------------------------------
library collexconv;

uses
ShareMem,
SysUtils,
Classes;

{$R *.res}
Function GrpNum (S: String): String; stdcall;
begin
Result := copy(S,1,1);
if Result = 'G' then begin
Result := copy(S,2,5);
Result := StringReplace(Result, ' ', '', [rfReplaceAll]); // is on line 1
end
else
Result := '';
end;
Function StartNum (S: String): String; stdcall;
begin
Result := copy(S,1,1);
if Result = 'A' then begin
Result := copy(S,2,5);
Result := StringReplace(Result, ' ', '', [rfReplaceAll]); // Is on line 2
end
else
Result := '';
end;

exports
GrpNum, StartNum;
end.
-----------------------------------------------------------------------------------------------

and the app is

----------------------------------------------------------------------------------------------
Uses
ShareMem;
Function GrpNum (S: String): String; stdcall; external 'collexconv.dll';
Function StartNum (S: String): String; stdcall; external 'collexconv.dll';

type
.........
........
.........

sl.LoadFromFile(CdrImportEdit.Text);
//loop though each line of text
for i := 0 to sl.count - 1 do
begin
group_no := GrpNum(sl[i]);
start_no := StartNum(sl[i]);
end;
-----------------------------------------------------------------------------------------------
I assume that in the app I can set an integer var, so that it is either line 0 or 1, but I then need to pass that info to the DLL so it can check it is reading the correct line.

_Katka_

Hi,

what about simply put another function to dll, like this:

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

ibrary collexconv;

uses
ShareMem,
SysUtils,
Classes;

{$R *.res}

{INSERTED BY KATE}

var
ActualLine:Integer; // here the actual line is stored

Procedure SetActualLine (Line: Integer); stdcall;
begin
ActualLine:=Line;
end;

{END OF INSERTION}

Function GrpNum (S: String): String; stdcall;
begin
Result := copy(S,1,1);
if Result = 'G' then begin
Result := copy(S,2,5);
Result := StringReplace(Result, ' ', '', [rfReplaceAll]); // is on line 1
end
else
Result := '';
end;
Function StartNum (S: String): String; stdcall;
begin
Result := copy(S,1,1);
if Result = 'A' then begin
Result := copy(S,2,5);
Result := StringReplace(Result, ' ', '', [rfReplaceAll]); // Is on line 2
end
else
Result := '';
end;

exports
{INSERTED BY KATE}
SetActualLine,
{END OF INSERTION}
GrpNum, StartNum;
end.

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

and then in application call this function every single cycle:

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

Uses
ShareMem;
Function GrpNum (S: String): String; stdcall; external 'collexconv.dll';
Function StartNum (S: String): String; stdcall; external 'collexconv.dll';

type
.........
........
.........

sl.LoadFromFile(CdrImportEdit.Text);
//loop though each line of text
for i := 0 to sl.count - 1 do
begin
{INSERTED BY KATE}
SetActualLine(I);
{END OF INSERTION}
group_no := GrpNum(sl[i]);
start_no := StartNum(sl[i]);
end;

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

than you'll have ActualLine variable available in GrpNum and StartNum functions..

regards,
Kate

lloydie-t

ASKER

Thanks for that Kate. I just need to inicate that the line number is either 0 or 1. Do you think the following would do that?

sl.LoadFromFile(CdrImportEdit.Text);
//loop though each line of text
for i := 0 to sl.count - 1 do
begin
{INSERTED BY KATE}
SetActualLine(Index);
{END OF INSERTION}
group_no := GrpNum(sl[i]);
start_no := StartNum(sl[i]);
{INSERTED BY LLOYD}
Inc (index)
if Index > 1 then
Index := 0;
{END OF INSERTION}
end;

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lloydie-t

ASKER

I was already thinking along the same lines and had already changed part of my code. Thanks for the confirmation. I suppose you can probably tell I am new to delphi so any info about the use of DLL's is helpful.

Member_2_248744

here is another DLL example

https://www.experts-exchange.com/questions/20633440/Creating-DLL-for-Delphi.html

Member_2_248744

also you can put very many parameters in a procedure or function in a DLL

procedure aProc(hWnd, aNum, aRef: Integer; aPnt: TPoint; aPchar: PChar; aRect: TRect);

you might look up "Parameters" and "Parameter semantics" and "Parameter passing" and "Calling conventions" in the delphi help, you can use the "var, const, and out " as types for a paraneter