Using a dll

Hello,

I'm trying to use a dll in a VB app. This dll as been written in C and can be used with a GUI made in Visual C++.

The fact is that I want to use only part of the dll's function in my app, so I don't want to be obliged to launch the GUI.

In my app, I've got a .bas with :
Public declare MyFunction lib "MyDll" (...)

In one of the function, I need to declare a variable which correspond in c to a cardinal, so :
- can someone tell me which is the corresponding variable in VB of a cardinal in c
- is declare ... lib "path of the dll" the right way to call for a dll

Thanks

Post the C declaration, and I'll try to translate it for you.

Also, here's a table that shows some of the common C declarations converted to VB.

Code:

---

BOOL        Long
WORD        Long
DWORD      Long
BYTE          Byte
LPSTR        String
float            Single
double        Double

---

Thanks Megatron,

here is the full procedure which I want to "copy" in VB


procedure TvStripForm.ParseIFO(FileName: String);
var
i, j: Integer;
ifo_handle, ifo_flags: Cardinal;
it: TTreeNode;
s: String;
begin
TreeViewIFO.Items.Clear();
IFOChainIdx := -1;
RadioGroupAngles.Items.Clear();
RadioGroupAngles.Enabled := False;
ListBoxIFOAudio.Items.Clear();
ListBoxIFOSub.Items.Clear();

for i := 0 to NumIFOChains - 1 do
if (IFOChains[i].Cells <> Nil) then begin
FreeMem(IFOChains[i].Cells);
IFOChains[i].Cells := Nil;
end;
SetLength(IFOChains, 0);
NumIFOChains := 0;

it := nil;
ifo_flags := 0;
case ComboBoxASPI.ItemIndex of
0: ifo_flags := ifo_flags + fio_USE_ASPI;
1: ifo_flags := ifo_flags + fio_USE_ASPI + vs_PREFER_ASPI;
end;

ifo_handle := ifoOpen(PChar(EditIFOName.Text), ifo_flags) ;
if (ifo_handle <> 0) then begin
j := ifoGetNumAudio(ifo_handle);
for i := 0 to j - 1 do
ListBoxIFOAudio.Items.Add(Format('%d. %s', [i, ifoGetAudioDesc(ifo_handle, i)]));

j := ifoGetNumSubPic(ifo_handle);
for i := 0 to j - 1 do
ListBoxIFOSub.Items.Add(Format('%d. %s', [i, ifoGetSubPicDesc(ifo_handle, i)]));

with TreeViewIFO.Items do begin
BeginUpdate();
NumIFOChains := ifoGetNumPGCI(ifo_handle);
SetLength(IFOChains, NumIFOChains);
for i := 0 to NumIFOChains - 1 do with IFOChains[i] do begin
NumCells := ifoGetPGCIInfo(ifo_handle, i, Length);
it := AddObject(nil, Format('%u. Length: %u:%.2u:%.2u:%.2u in %d cell(s)', [i, Length[0], Length[1], Length[2], Length[3], NumCells]), Pointer(i));
GetMem(Cells, NumCells * SizeOf(t_vs_vobcellid));
ifoGetPGCICells(ifo_handle, i, @Cells^[0]);
for j := 0 to NumCells - 1 do with Cells[j] do begin
s := Format('%u. V: %.3u/C: %.3u', [j, vob_id, cell_id]);
if (angle <> $11) then
s := s + Format(' (%u/%u)', [angle and $f, angle shr 4]);
s := s + Format(' [@LBA %u - %u]', [start_lba, end_lba]);
AddChildObject(it, s, Pointer(j));
end;
end;
if ((it <> nil) and (NumIFOChains = 1)) then
TreeViewIFO.Selected := it;
EndUpdate();
end;
ifoClose(ifo_handle);
end else
MessageDlg('vStrip could not read/parse the IFO-File', mtError, [mbOK], 0);
end;

In red, you have the function I can't cope with in VB. I guess that if I can have this one work, I'll have the others too.

for info, this is part of the source code of vSrtip, that you could find on the source code section of download section of http://www.doom9.org/

thanks for your help

That's Pascal, not C.

Anyways, if it's in the DLL, all you would need to convert it to a VB declaration is:

Code:

---

Private Declare Function MyFunc Lib "MyLib" Alias "ActualFunctionName" (ByVal Filename As String)

---

Use Dependancy Walker to get the "ActualFileName"

Thanks Megatron

As I know really nothing to C I supposed it was C.

So, I don't need to "convert" the second part of the call to the function ie ifoOpen(PChar(EditIFOName.Text), ifo_flags )

Thank you anyway

PChar looks like it's being used as a function, rather than a datatype.

Code:

---

PChar(EditIFOName.Text)

---

:D
That was so easy that I should have guess it by myself

Thank you a lot

:confused:
My version of VB (6) seems not to know PChar function...
Maybe I'm doing something wrong.
:confused: