用QT实现计时器功能

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

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QTimer>
#include <QTime>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow{
    Q_OBJECT
public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
private slots:
    void initTime();
    void updateTime();
    void pbStart_clicked();
private:
    Ui::MainWindow *ui;
    QTimer * timer;
    QTime * TimeRecord;
};
#endif // MAINWINDOW_H

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent) , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    timer = new QTimer;
    TimeRecord = new QTime;
    ui->Timer->setDigitCount(8);
    initTime();     //令LCD显示00:00:00
    //连接槽函数，将timer的timeout行为，连接到updateTime函数中
    connect(timer, SIGNAL(timeout()), this, SLOT(updateTime()));
    //当点击(clicked)pbStart时，调用函数pbStart_clicked
    connect(ui->pbStart, SIGNAL(clicked()), this, SLOT(pbStart_clicked()));
}

MainWindow::~MainWindow(){
    delete ui;
}

void MainWindow::initTime(){
    TimeRecord->setHMS(0, 0, 0); //时间复位为0
    ui->Timer->display(TimeRecord->toString("hh:mm:ss"));
}

void MainWindow::updateTime(){
    //每次更新时间，TimeRecord增加1
    *TimeRecord = TimeRecord->addSecs(1);
    ui->Timer->display(TimeRecord->toString("hh:mm:ss"));
}

void MainWindow::pbStart_clicked(){
    if (QString::compare(ui->pbStart->text(),"stop")){
        //当按钮内容不为'stop'时，说明开启计时
        timer->start(1000);
        ui->pbStart->setText("stop");//计时开始后，按钮变为'stop'
    }else{
        timer->stop();
        ui->pbStart->setText("start");
        initTime();
    }
}