How to include a interface of a .dll file

[Subhash]

Hi,
I am new to this forum,I am able to include a dll library in my program but i dont know how to create a object of a interface present in the dll file.
I would like to call a interface called ICamera2Ptr which is present in Apogee.dll.

Can anyone help to do it?
If code is needed we will post it.

[goetz]

You will need the header files of the library, usually located in a directory named "include". Add the directory to the include path of your project like this:

@
INCLUDEPATH += /path/to/your/lib/include
@

[sven.bergner]

If you want to load the dll dynamiclly you should have a look at QLibrary.

[Subhash]

hi,
thanks for the reply we r appending our code so far
@#include <QtCore/QCoreApplication>
#include<stdio.h>
#include<QLibrary.h>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QLibrary asd("C:/subh/Apogee");
typedef void (*ICamera2Ptr)();

ICamera2Ptr d;
bool ab,c;
ab=asd.load();
if(asd.isLoaded()==true)

{
    printf("Loaded properly");
    c=d.ShowDialog(true);

}
else
{
    printf("not loaded");
}
return a.exec();

}
@
but we are able to include the dll in our program but when we try to implement any of the member functions in it v are getting an error..
request to member-function"ShowDialog" in 'd',which is a non-class type 'void(*)()'

[goetz]

"QLibrary docs":http://doc.qt.nokia.com/4.7/qlibrary.html has the answer:

The symbol must be exported as a C function from the library...

The most important functions are load() to dynamically load the library file, isLoaded() to check whether loading was successful, and resolve() to resolve a symbol in the library

Your symbol seems to be a C++ one, and you did not call resolve() (which would fail, as it searches for C symbols).

From what I see it seems to be a problem that is not solved by using QLibrary but by linking to the DLL/lib at compile time (and using the correct header files).

[Subhash]

[quote author="Volker" date="1298044820"]"QLibrary docs":http://doc.qt.nokia.com/4.7/qlibrary.html has the answer:

The symbol must be exported as a C function from the library...

The most important functions are load() to dynamically load the library file, isLoaded() to check whether loading was successful, and resolve() to resolve a symbol in the library

Your symbol seems to be a C++ one, and you did not call resolve() (which would fail, as it searches for C symbols).

From what I see it seems to be a problem that is not solved by using QLibrary but by linking to the DLL/lib at compile time (and using the correct header files).
[/quote]

I am Sorry but can u explain how to export it as C symbol and how to solve this error..Please help me.

[goetz]

RTFM. The link is in my first comment.