Use of a DLL written in Delphi Xe2

Zoptune

Hi,

I have to use functions from a Delphi Xe2 DLL and i'm having some troubles.

I use QLibrary to dynamically load the DLL at run time. All the functions are found in the DLL by the resolve function but when i call the first function (init function) my app crashes and exit with code 0.

Maybe the problem comes from my function prototypes definition :

typedef int (WINAPI *Init_ptr) ();

In the doc :
"Function Init : integer ; stdcall "
return 0 if no error

It's the first time i'm using a library (moreover in Delphi) so i don't know where is the problem.

Any help/explanation about my problem or about DLL in general will be useful.

Thx

jsulm

@Zoptune Did you verify that Init_ptr actually points to the function?

Zoptune

@jsulm Yes... i think ^^

typedef int (WINAPI *Init_ptr) ();

Init_ptr Init=NULL;
if(lib->load()){
    Init=(Init_ptr)lib->resolve("Init");
}
if(Init!=NULL){
    int res=Init();  // The app crashes here
}

Am I doing something wrong ?

jsulm

@Zoptune Looks good. Do you have a stack trace?

kshegunov

@Zoptune
By the way, is there a special reason for not leaving the OS loader to resolve the symbols instead of explicitly doing it with QLibrary?

lemmel

@Zoptune
Your doc doesn't seems to be helpful.

Are you sure that this library is operational with your build ? I know that Windows doesn't like to mix library build mixed (one with CRT of Visual Studio 2003, with another library using the crt of Visual Studio 2015).

Furthermore « crash » is not helpful, because the cause of the crash maybe intern to your library (i.e. you make a good call, but the library doesn't initialize well); don't you have an error message/code ?

Did you test to load that library with a regular and plain hello world in visual studio ?

Hope all my questions will help you.

P.S. : I suppose that you don't have the code of the library but must use it ? Can't you ask the support an C++ example ?

Zoptune

@jsulm
@kshegunov
@lemmel

Thx all for your replys. The problem came from inside the function of the DLL.

In fact, the library allow me to do some task on a machine.
This machine is connected to my LAN.

The problem was that the machine has a fixed IP address and this IP was out of my LAN.
Had to use Wireshark to find the problem ^^

Thx for help :)