C++ Qt 62 - Viewer Feedback Signals and Slots in depth 

Love your videos man... Easier than listening to Indian accent (No offense, Indian community) and very clear teaching method. I grant you 100 coolness points.

One major stumbling block for me was realizing that many kinds of “emit” statements happen automatically, that you don’t need to declare them. For example, say you create a button with object name of pushButton, if you right click on the button in the designer and choose “Go to slot..” and choose “clicked()”, Qt creator will fill out the stub implementation and the declaration for it in the header under slots. Now for this function (I.e. slot) to be called, the only thing that needs to be done is for user to click on the button. You don’t have to code an emit for these common actions (basically any of the ones you see listed when you choose “go to slot...”). You only need to emit a signal when you are defining one that isn’t built in to Qt and emitted automatically, like a custom one. This really confused me for a while-I didn’t realize Qt would auto emit clicked() signal and coded my own, the result being that my slot for the button clicked signal would be called twice!

Thank you so much. I was with so much difficult but now i really know implement signals and slots in my QT projects.

Thanks for this! Have an exam today on QT so this has helped me with the basics needed for signals and slots. Quite easy when explained properly. :) Now on to run through the Observer design pattern

This is an excellent video, thanks a lot :) Hope this message receives you and your loved ones in perfect health, best regards from Norway :)

Pure example of "old but gold" Thanks a million bro...

Brain, you're just awesome man. Love all your videos.

I really love your videos which make me learn a lot of knowledge and how to be a good educator. thank you so much.

Thank you very much for your great tutorial! Very helpfull!

wow I really understood. This example is so compatible for signal and slots. You're like teacher, good one.

awesome tutorial, now i understood signals and slots much better!

you are a great human being

Nice video man! Thanks

Great tutorial! Thank you very much.

i am learning alot from your videos. you are next level superhero :D

No need for the WaterCooler. You could have created and connected Cathy and Bob in main() too.

haha great start :D

TIMELINE!! I'm trying to add slots to my MainWindow class, but my connection isn't firing. Is it because MainWindow is already inheriting from QMainWindow?

from the slot you can access the sender: QObject::sender() "Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns 0. The pointer is valid only during the execution of the slot that calls this function from this object's thread context."

Thank you so much, Nice Vedio

Great videos man. You're really at another level in teaching. Anyway, questions: In the person header, you define void Listen under the slots section, but also define it in person.cpp. To gauge my understanding, I was playing around and defined void Person::Speak { } in person.cpp . Not too surprisingly, the compiler complained about fcn definitions in the same class. But why does it not matter that void Listen is defined twice? Thanks !

Thank you for sharing. Can you please tell us about some real time usage of s & s as well?

Hi I have a question. Do you know why when I try to do a signal slot it says something like "function" was not declared even though in the header file i did signals: void update(); and in a function in the .cpp file I did (along with some other code) emit update();

Hey Bryan, I am developing a desktop app and it has lots of QLineEdit controls. I wanted to capture the lostFocus signal on each of them and do a validation. Can you please help me on how to do it? From the help docs, I understood I need to override the focusOutEvent(QFocusEvent * e). However I am stuck here on how to write this code and into which file (mainwindow.cpp or some where else)... Please help me. I am really stuck... :(

Wow, that was really hard to wrap my head around. I need to watch this video a few more times... Do you have any videos (besides the very first one) that explain how to use signals and slots in a Gui application?

Can this be done between objects of a diferent type?

Isnt there any way of setting up a 2 way communication easier than defining signals and slots one way twice?

ah, okay I was trying to connect in main; I bet that'll solve some of my issues lol.

It would make so much more intuitive sense if SIGNALS were not VOID. But the signal-slot system now makes sense in a way that it bridges exactly this gap. So the SLOTS get all params of SIGNALS, thats how this works, right?

omg because of the crap school i never heard about this in 2011

You also could make Chatty Cathy to listen to Silly Sally and create real life situation

In Qt 5 signals are public.

This doesn't work now

Silly Sally

hi brayn please let me know ur mail id or home page ,i am very much appropriate videos for the qt beginners , thanks very much

wow NOT an INDIAN guy!!!!!!!!!!! Runtime error;;;;;;;;;;