Solved

Classes in Dll

Posted on 1997-05-16
3
186 Views
Last Modified: 2010-04-04
I have a class build in c++ in a Dll.
Can anyone tell me how can i use it in delphi 2.0?
Thank you.

0
Comment
Question by:Nuno Alves
  • 2
3 Comments
 
LVL 3

Accepted Solution

by:
sperling earned 50 total points
ID: 1336344
Create a similar virtual and abstract class in delphi 2. Get the address of a instance of the C++ class, and cast this address to the delphi class.


e.g.

type

  TClassCorrespondingToDllClass = class
    function FirstMethodInCPPClass : INTEGER; stdcall; virtual; abstract;
    procedure SecondMethodInCPPClass; stdcall; virtual; abstract;
  end;


Then

var
  TheObject : TClassCorrespondingToDllClass;

begin
  TheObject := TClassCorrespondingToDllClass ( DLLFunctionCreatingTheClassAndReturningPointer)

  TheObject.SecondMethod;
end;

If your delphi class maps *exactly* to the c++ class (calling convention and parameters), this should work. You need to have the DLL create an instance of the class though.

Regards,

Erik.
0
 
LVL 1

Author Comment

by:Nuno Alves
ID: 1336345
How can I load the dll in delphi?
I now that with the dll in C I just have to put before
the declaration of the function external 'Dll name' but
with the class i couldn't do the same.
0
 
LVL 3

Expert Comment

by:sperling
ID: 1336346
You have to declare an exported function in the C DLL. This function should create an instance of the class and return it as a pointer. I can't be of much help when it comes to C syntax...

Import it into delphi like this:

function CreateAnObject : POINTER; stdcall; external 'DLLNAME.DLL' name 'ExportedNameOfCreateAnObject';


Regards,

Erik.
0

Featured Post

Live: Real-Time Solutions, Start Here

Receive instant 1:1 support from technology experts, using our real-time conversation and whiteboard interface. Your first 5 minutes are always free.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Delphi XE10, MySQL Query 4 143
error 1.1 400 Bad request idhttp delphi 18 87
Help on project with Soap 10 53
enhance the following code 3 31
The uses clause is one of those things that just tends to grow and grow. Most of the time this is in the main form, as it's from this form that all others are called. If you have a big application (including many forms), the uses clause in the in…
Creating an auto free TStringList The TStringList is a basic and frequently used object in Delphi. On many occasions, you may want to create a temporary list, process some items in the list and be done with the list. In such cases, you have to…
This Micro Tutorial will give you a basic overview how to record your screen with Microsoft Expression Encoder. This program is still free and open for the public to download. This will be demonstrated using Microsoft Expression Encoder 4.
In a recent question (https://www.experts-exchange.com/questions/28997919/Pagination-in-Adobe-Acrobat.html) here at Experts Exchange, a member asked how to add page numbers to a PDF file using Adobe Acrobat XI Pro. This short video Micro Tutorial sh…

776 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question