Application example of Qtemitsignal

In Qt, you can use QObject::emitmethods to emit (emit) a signal. Calling the emit method immediately executes the slot function associated with that signal.

Here's an example that demonstrates how to emitemit a signal using a method:

#include <QtCore>

class MyObject : public QObject {
    Q_OBJECT
public:
    explicit MyObject(QObject *parent = nullptr) : QObject(parent) {}

signals:
     void mySignal();

public slots:
    void mySlot() {
        qDebug() << "My slot is called";
    }
};

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);

    MyObject obj;
    QObject::connect(&obj, &MyObject::mySignal, &obj, &MyObject::mySlot);

    qDebug() << "Before emit";
    emit obj.mySignal();
    qDebug() << "After emit";

    return app.exec();
}

#include "main.moc"

In the above example, we defined a simple QObject subclass named MyObject, which contains a signal mySignal and a slot function mySlot. Then, we create a MyObject instance in the main() function and connect the mySignal signal with the mySlot slot function. Finally, we emitemit a mySignal signal using the method and log the event on output.

When we run the above program, we will see output similar to the following:

Before emit
My slot is called
After emit

In the output, we can see that when we use emit obj.mySignal()the emit signal, the signal immediately triggers the mySlot slot function to print "My slot is called".

Note that since we emithave a signal that executes the slot function immediately, we must ensure that the slot function is properly connected to the signal. Otherwise, undefined behavior may result.

Hope this helps you understand how to use emitmethods to emit a signal.

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Application example of Qtemitsignal

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