Qt - custom signal sending an integer

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I have an array of custom buttons. I want to create a custom signal, which, when connected to a slot, which takes an integer as an argument, will send a variable to it.
So for example, let's say I've got 10 buttons, each of them has an id from 0 to 9. I connect all of them to a single function, which takes an integer argument. The function, when called, prints it's argument. Now when I press button 4, I want to see a 4 printed on my screen.

I've never created a custom signal before, so I'd be very grateful for any help.

What I have tried:

I haven't tried anything yet. I've only created the class.

Posted 26-Aug-18 0:52am

Member 13020023

Updated 27-Aug-18 1:47am

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Richard MacCutchan 26-Aug-18 11:29am

You have 10 buttons each of which has an id. So when your function gets called you just need to identify which button called it. I don't know how this works in Qt, in C# the button id would be sent to the function.

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Jochen Arndt · Answer 1 · 2018-08-27T01:48:00

Just implement a QPushButton::clicked() slot that is connected to multiple push buttons. Inside that cast sender() to QPushButton* to access the button and identify it. You can then emit a user defined signal with additional parameters.

Another method would be using a C++11 lambda:

C++

int counter = 1;

// Create button or access it using the ui member 
//QPushButton *button = new QPushButton;

button->setProperty("myId", counter++);
connect(button, &QPushButton::clicked, [this, button](){
    qDebug() << button->property("myId").toString();
    ui->label->setText(button->text());
});

// Repeat for the other buttons

The above is using the property system to provide IDs, printing it to the debug window and setting a label to the button's caption text.