Qt中使用QLabel顯示時間的兩種方法

其實這兩種方法思路一致，只是實現方法不一樣而已。

main.cpp

#include "displaytime.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    DisplayTime w;
    w.show();
    
    return a.exec();
}

方法一：

displaytime.h

#ifndef DISPLAYTIME_H
#define DISPLAYTIME_H

#include <QWidget>
#include <QtGui>

class QLabel;

class DisplayTime : public QWidget
{
    Q_OBJECT
    
public:
    DisplayTime(QWidget *parent = 0);
    ~DisplayTime();

private:
    QLabel *timeLabel;

protected:
    void timerEvent(QTimerEvent * event);
};

#endif // DISPLAYTIME_H

displaytime.cpp

#include "displaytime.h"

DisplayTime::DisplayTime(QWidget *parent)
    : QWidget(parent)
{
    timeLabel = new QLabel(this);
    timerEvent(0);
    startTimer(1000);
    timeLabel->show();
}

DisplayTime::~DisplayTime()
{
    
}

void DisplayTime::timerEvent(QTimerEvent *event)
{
    Q_UNUSED(event);
    timeLabel->setText(QTime::currentTime().toString("hh:mm:ss"));
}

方法二：

displaytime.h

#ifndef DISPLAYTIME_H
#define DISPLAYTIME_H

#include <QWidget>
#include <QtGui>

class QLabel;

class DisplayTime : public QWidget
{
    Q_OBJECT
    
public:
    DisplayTime(QWidget *parent = 0);
    ~DisplayTime();

private:
    QLabel *timeLabel;

private slots:
    void updateTime();
};

#endif // DISPLAYTIME_H

displaytime.cpp

#include "displaytime.h"

DisplayTime::DisplayTime(QWidget *parent)
    : QWidget(parent)
{
    timeLabel = new QLabel(this);
    timeLabel->setGeometry(0, 0, 150, 30);

    QTimer *timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()),
            this, SLOT(updateTime()));
    timer->start(1000);

    timeLabel->show();
}

DisplayTime::~DisplayTime()
{
    
}

void DisplayTime::updateTime()
{
    timeLabel->setText(QDateTime::currentDateTime().toString("hh:mm:ss"));
}