QTimer signalSlot

//-------------------- .h -----------------------------

#ifndef MAINWINDOW_H

#define MAINWINDOW_H
#include <QMainWindow>
#include <QTimer>
#include <QDebug>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
   Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

   private slots:
    void updates();

private:
    Ui::MainWindow *ui;
    QTimer *timer;

};

#endif // MAINWINDOW_H

//------------------------ .cpp ----------------

#include "mainwindow.h"

#include "ui_mainwindow.h"

int cnt =0;

MainWindow::MainWindow(QWidget *parent) :

    QMainWindow(parent),

    ui(new Ui::MainWindow)

{

    ui->setupUi(this);

    QTimer *timer = new QTimer(this);

       connect(timer, SIGNAL(timeout()), this, SLOT(updates()));

       timer->start(300);

}

MainWindow::~MainWindow()

{

    delete ui;

}

void MainWindow::updates(){

cnt++;

qDebug() << "Timer = " << cnt;

}