How to use QTimer

Question

In Qt I'm trying to set a QTimer that calls a function called "update" every second. Here is my .cpp file:

#include "mainwindow.h" #include "ui_mainwindow.h" #include <QTimer> #include "QDebug"  MainWindow::MainWindow(QWidget *parent) :     QMainWindow(parent),     ui(new Ui::MainWindow) {     ui->setupUi(this);      QTimer *timer = new QTimer(this);     connect(timer, SIGNAL(timeout()), this, SLOT(update()));     timer->start(1000); }  MainWindow::~MainWindow() {     delete ui; }  void MainWindow::update() {     qDebug() << "update"; } 

and the main:

#include <QtGui/QApplication> #include "mainwindow.h"  int main(int argc, char *argv[]) {     QApplication a(argc, argv);     MainWindow w;     w.show();      return a.exec(); } 

The project is being build, but it doesn't execute update, since the line "update" is not showing anywhere... Does anybody see what I´m doing wrong?

Answer 1

Other way is using of built-in method start timer & event TimerEvent.

Header:

#ifndef MAINWINDOW_H #define MAINWINDOW_H  #include <QMainWindow>  namespace Ui { class MainWindow; }  class MainWindow : public QMainWindow {     Q_OBJECT  public:     explicit MainWindow(QWidget *parent = 0);     ~MainWindow();  private:     Ui::MainWindow *ui;     int timerId;  protected:     void timerEvent(QTimerEvent *event); };  #endif // MAINWINDOW_H 

Source:

#include "mainwindow.h" #include "ui_mainwindow.h" #include <QDebug>  MainWindow::MainWindow(QWidget *parent) :     QMainWindow(parent),     ui(new Ui::MainWindow) {     ui->setupUi(this);      timerId = startTimer(1000); }  MainWindow::~MainWindow() {     killTimer(timerId);     delete ui; }  void MainWindow::timerEvent(QTimerEvent *event) {     qDebug() << "Update..."; }