QTimer Not Triggering Slot in Qt Application

[skylerclooney]

Hi everyone,

I’m having trouble with a `QTimer` that doesn’t seem to trigger its slot. The timer starts without errors, but the timeout function is never called.

Here is a simplified version of my code:

#include <QApplication>
#include <QMainWindow>
#include <QTimer>
#include <QDebug>
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    MainWindow(QWidget *parent = nullptr)
        : QMainWindow(parent)
    {
        QTimer *timer = new QTimer(this);
        connect(timer, &QTimer::timeout, this, &MainWindow::onTimeout);
        timer->start(1000);  // 1 second
    }
 
private slots:
    void onTimeout()
    {
        qDebug() << "Timer triggered";
    }
};
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

#include <QApplication>
#include <QMainWindow>
#include <QTimer>
#include <QDebug>

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr)
        : QMainWindow(parent)
    {
        QTimer *timer = new QTimer(this);
        connect(timer, &QTimer::timeout, this, &MainWindow::onTimeout);
        timer->start(1000);  // 1 second
    }

private slots:
    void onTimeout()
    {
        qDebug() << "Timer triggered";
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

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The application runs fine, but "Timer triggered" never appears in the console.
Am I missing something related to the event loop or object lifetime?
Is there something wrong with how I’m creating or connecting the timer?

[wysota]

The code looks okay. Does this simplified version also not work for you?