How to stop QElapsedTimer?

Question

    QElapsedTimer timer;
    timer.start();

    slowOperation1();

    qDebug() << "The slow operation took" << timer.elapsed() << "milliseconds";

http://doc.qt.io/qt-5/qelapsedtimer.html#invalidate

After qDebug() I would want to stop this timer. I can't see a stop function there, nor a single shot property.

What's the way out?

Answer 1

You can't stop QElapsedTimer, because there is no timer. When you call method start(), QElapsedTimer saves the current time.

From qelapsedtimer_generic.cpp

void QElapsedTimer::start() Q_DECL_NOTHROW
{
    restart();
}

qint64 QElapsedTimer::restart() Q_DECL_NOTHROW
{
    qint64 old = t1;
    t1 = QDateTime::currentMSecsSinceEpoch();
    t2 = 0;
    return t1 - old;
}

When elapsed, it gets current time again, and calculate difference.

qint64 QElapsedTimer::elapsed() const Q_DECL_NOTHROW
{
    return QDateTime::currentMSecsSinceEpoch() - t1;
}

P.S. Specific realization is platform dependent: Windows, Unix, Mac