DLL

How can I create dll's and then use them in VB?
LVL 1
truninAsked:
Who is Participating?
 
DrDelphiCommented:
All true what rondi is saying.... once you've compiled the DLL, you use it like you would any other DLL in VB.

Delphi:
library thedate;

{ Important note about DLL memory management: ShareMem must be the
  first unit in your library's USES clause AND your project's (select
  View-Project 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 DELPHIMM.DLL shared memory manager, which must be deployed along
  with your DLL. To avoid using DELPHIMM.DLL, pass string information
  using PChar or ShortString parameters. }

uses
  SysUtils,
  Classes;
   var mydate:pchar;
      function makeitaday(S:integer):pchar;stdcall;
     var thedate:array[0..20] of char;

      begin
     GetMem(mydate, 200);
     if s=1 then thedate:='Sunday ';
     if s=2 then thedate:='Monday ';
     if s=3 then thedate:='Tuesday ';
     if s=4 then thedate:='Wednesday ';
     if s= 5 then thedate:='Thursday ';
     if s = 6 then thedate:='Friday ';
     if s= 7 then thedate:='Saturday ';
     strpcopy(mydate,thedate);
     makeitaday:=mydate;
     end;
         
 exports makeitaday;
     begin
      end.
 


VB:

Private Declare Function makeitaday Lib "thedate.dll" (ByVal day As Integer) As String


Private Sub Command1_Click()
MsgBox makeitaday(2)
'this shows "Monday"
End Sub


Good luck!!
0
 
DrDelphiCommented:
I have a simple example on my website:

http://www.drdelphi.com/delphi/right/tips/dll.htm

Good luck!!
0
 
truninAuthor Commented:
And how can I use dll in VB? I need a simple example of using delphi dll in VB.
0
 
rondiCommented:
In a module type something like:

Public Declare Function DelphiFunc Lib "MyDelphiDLL.dll" (ByVal TestInt As Long) As Long

or for a procedure:

Public Declare Sub DelphiProc Lib "MyDelphiDLL.dll" (ByVal TestStr As String)

Your Delphi DLL unit would look something like:


library MyDelphiDLL;

...
....

uses Windows;
...
...

function DelphiFunc(TestInt: integer): integer;
begin
  Result := TestInt * 2;
end;

procedure DelphiProc(TestStr: PChar);
begin
  MessageBox(Application.Handle,TestStr,'DelphiProc', MB_OK or MB_APPMODAL);
end;

...
...

exports DelphiFunc, DelphiProc;
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