Qt Centre Forum - Qt Programming https://www.qtcentre.org/ General more advanced Qt programming issues. en Sat, 07 Mar 2026 06:15:43 GMT vBulletin 15 https://qtcentre.org/images/misc/rss.png Qt Centre Forum - Qt Programming https://www.qtcentre.org/ QTimer Not Triggering Slot in Qt Application https://qtcentre.org/threads/72289-QTimer-Not-Triggering-Slot-in-Qt-Application?goto=newpost Tue, 03 Mar 2026 07:05:43 GMT 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... 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:

Code:
  1. #include <QApplication>
  2. #include <QMainWindow>
  3. #include <QTimer>
  4. #include <QDebug>
  5.  
  6. class MainWindow : public QMainWindow
  7. {
  8.     Q_OBJECT
  9.  
  10. public:
  11.     MainWindow(QWidget *parent = nullptr)
  12.         : QMainWindow(parent)
  13.     {
  14.         QTimer *timer = new QTimer(this);
  15.         connect(timer, &QTimer::timeout, this, &MainWindow::onTimeout);
  16.         timer->start(1000);  // 1 second
  17.     }
  18.  
  19. private slots:
  20.     void onTimeout()
  21.     {
  22.         qDebug() << "Timer triggered";
  23.     }
  24. };
  25.  
  26. int main(int argc, char *argv[])
  27. {
  28.     QApplication a(argc, argv);
  29.     MainWindow w;
  30.     w.show();
  31.     return a.exec();
  32. }

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? ]]> Qt Programming skylerclooney https://qtcentre.org/threads/72289-QTimer-Not-Triggering-Slot-in-Qt-Application