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POIn Qt how do I get a button press to set a spinbox to a certain value?
 

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  1. POIn Qt how do I get a button press to set a spinbox to a certain value?
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    <p>I'm trying to get to grips with Qt's signal and slots mechanism. I have an app with a QPushButton and a QSpinBox. When I click the button I want the spinbox to change to 20. What signal and slot do I need to set up?</p> <p>The code below shows the app, the connect function is the one I am having trouble with. As I understand it the setValue(int) slot of QSpinBox will not work here because the clicked() signal of QPushButton has a different signature, and anyway how would I pass the value 20 to the spinbox? Do I need to write some sort of auxiliary function to act as a slot which calls spinbox->setValue(20)? If so, what form would that take?</p> <pre><code>int main(int argc, char *argv[]) { QApplication app(argc, argv); QWidget *window = new QWidget; QSpinBox *spinbox = new QSpinBox; QPushButton *button = new QPushButton("Set to 20"); spinbox-&gt;setRange(0, 100); // What should I put below? QObject::connect(button, SIGNAL(clicked()), spinbox, SLOT(???????)); QLayout *layout = new QHBoxLayout; layout-&gt;addWidget(spinbox); layout-&gt;addWidget(button); window-&gt;setLayout(layout); window-&gt;show(); return app.exec(); } </code></pre>
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    1. USPowerApp101
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    1. CODocumentation has everything you need. I recommend to start with this one: http://doc.trolltech.com/4.5/signalsandslots.html
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    2. CONothing in there tells me what I need to know.
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    3. COReally? The signals and slots mechanism is type safe: The signature of a signal must match the signature of the receiving slot. And there are several simple examples which cover your question.
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