Now timer is working but cannot stop.
Qt Code: 
  1. #include "form1.h"
  2. #include "ui_form1.h"
  3.  
  4.  
  5. #include <QTimer>
  6. #include <QTime>
  7.  
  8.  
  9. Form1::Form1(QWidget *parent) :
  10.     QWidget(parent),
  11.     ui(new Ui::Form1)
  12. {
  13.     ui->setupUi(this);
  14.  
  15.  
  16.    time.setHMS(0,0,0,0);
  17.    i=0;
  18.    ui->lcdNumber->setNumDigits(8);
  19.    QString text = time.toString("hh:mm:ss");
  20.    ui->lcdNumber->display(text);
  21. }
  22.  
  23. Form1::~Form1()
  24. {
  25.     delete ui;
  26. }
  27.  
  28. void Form1::startTime()
  29. {
  30.     QTimer *timer=new QTimer(this);
  31.     connect(timer, SIGNAL(timeout()), this, SLOT(showTime()));
  32.     timer->start(1000);
  33. }
  34.  
  35. void Form1::showTime()
  36. {
  37.     QTime newtime;
  38.     i=i+1;
  39.     newtime=time.addSecs(i);
  40.     QString text = newtime.toString("hh:mm:ss");
  41.     ui->lcdNumber->display(text);
  42.  
  43. }
  44.  
  45. void Form1::stopTime()
  46. {
  47.     QTimer *timer=new QTimer(this);
  48.     timer->stop();
  49. }
To copy to clipboard, switch view to plain text mode