[QXmpp] Trying to use sendMessage to a MUC crashes my app.

[jsulm]

@SrisharanVS said in [QXmpp] Trying to use sendMessage to a MUC crashes my app.:

room_ptr->sendMessage("SOME MESSAGE"); //triggers crash

How is room_ptr initialized in function_2?
There is also debugger to debug such issues.

[SrisharanVS]

@jsulm Do I need to,

room_ptr = m_mucManager->addRoom(roomJid);
room_ptr->setNickName("Player 1");
room_ptr->join();

in every different funcion before trying sendMessage()? Can you be more specific about initialization?

This was the error I got and also,

[jsulm]

@SrisharanVS said in [QXmpp] Trying to use sendMessage to a MUC crashes my app.:

Can you be more specific about initialization?

You need to make sure room_ptr is a valid pointer before you use it. You did not post the code of the function_2, so nobody knows whether it is initialised. In function_1 you assign something to room_ptr, but we do not know whether room_ptr is a local variable in that function or class member. Yeasiest way to share something inside a class is to make it class member (in that case make room_ptr class member).

[JonB]

@SrisharanVS
As @jsulm has said. And as he wrote before you should look at this in a debugger yourself. You absolutely need to learn to do debugging for C++ programs, and the sooner you learn to use and are confident with a debugger the better, it will be you who benefits from it over time.

Here we don't know, but the first thing is see the stack trace from the crash/signal and look at the value of room_ptr if it's dying on room_ptr->sendMessage().

[SGaist]

Hi,

Beside using a debugger to pinpoint where your application fails, you should also check whether your room_ptr is null before using it. You might be calling things out of the order you think they are happening.

[Christian Ehrlicher]

You set room_ptr to nullptr in various branches of your code - so I would guess it's a nullptr in your second call.

[SrisharanVS]

@Christian-Ehrlicher

I tried to print the value of room->ptr before room_ptr->sendMessage(), and its zero, I not sure how it becomes 0 though..

I set room->ptr to nullptr on ::left, ::kicked. That was me trying to debug things, the problem existed without it too.. I added those to see if and when my user disconnects from the MUC, but there were never triggered.

[Christian Ehrlicher]

Then you never set it to something! = nullptr

[SrisharanVS]

But I do the below,

room_ptr = m_mucManager->addRoom(roomJid);
room_ptr->setNickName("Player 1");
room_ptr->join();
connect(room_ptr, &QXmppMucRoom::joined, this,
                        [this, player, board]() {
                            std::cout << "Joined room: " << room_ptr->jid().toStdString();
                            std::cout << "room: " << room_ptr << std::endl;
                            if(room_ptr->isJoined()) {
                                std::cout << "STILL JOINED" << std::endl << std::flush;
                            }
                            emit gameInviteAccepted("Sender", player, board);
                            room_ptr->sendMessage("THIS IS A TEST MESSAGE");
                        });

And room_ptr is a class member. Only when gameInviteAccepted is emitted, then I am pushed into a screen, where I am able to trigger sendGameMove(), so sendGameMove is definitely happening after the above code, since emit is inside connect.

Here, I get some address for room_ptr, but then in the other function, I get a 0

[SrisharanVS]

Thank you everyone for taking your time to reply me. The mistake was that, the invokation of the functions were in different qml files, and I had used different instances of the class in the 2 files. I finally fixed it :)