qdatetime.cpp

奇趣公司比较新的qt/emd版本

    the format of the result string.

    These expressions may be used:

    \table
    \header \i Expression \i Output
    \row \i h
         \i the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
    \row \i hh
         \i the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
    \row \i H
         \i the hour without a leading zero (0 to 23, even with AM/PM display)
    \row \i HH
         \i the hour with a leading zero (00 to 23, even with AM/PM display)
    \row \i m \i the minute without a leading zero (0 to 59)
    \row \i mm \i the minute with a leading zero (00 to 59)
    \row \i s \i the second without a leading zero (0 to 59)
    \row \i ss \i the second with a leading zero (00 to 59)
    \row \i z \i the milliseconds without leading zeroes (0 to 999)
    \row \i zzz \i the milliseconds with leading zeroes (000 to 999)
    \row \i AP or A
         \i use AM/PM display. \e AP will be replaced by either "AM" or "PM".
    \row \i ap or a
         \i use am/pm display. \e ap will be replaced by either "am" or "pm".
    \endtable

    All other input characters will be ignored. Any sequence of characters that
    are enclosed in singlequotes will be treated as text and not be used as an
    expression. Two consecutive singlequotes ("''") are replaced by a singlequote
    in the output.

    Example format strings (assuming that the QTime is 14:13:09.042)

    \table
    \header \i Format \i Result
    \row \i hh:mm:ss.zzz \i 14:13:09.042
    \row \i h:m:s ap     \i 2:13:9 pm
    \row \i H:m:s a      \i 14:13:9 pm
    \endtable

    If the datetime is invalid, an empty string will be returned.

    \sa QDate::toString() QDateTime::toString()
*/
QString QTime::toString(const QString& format) const
{
    return fmtDateTime(format, this, 0);
}
#endif //QT_NO_DATESTRING
/*!
    Sets the time to hour \a h, minute \a m, seconds \a s and
    milliseconds \a ms.

    \a h must be in the range 0 to 23, \a m and \a s must be in the
    range 0 to 59, and \a ms must be in the range 0 to 999.
    Returns true if the set time is valid; otherwise returns false.

    \sa isValid()
*/

bool QTime::setHMS(int h, int m, int s, int ms)
{
    if (!isValid(h,m,s,ms)) {
        mds = NullTime;                // make this invalid
        return false;
    }
    mds = (h*SECS_PER_HOUR + m*SECS_PER_MIN + s)*1000 + ms;
    return true;
}

/*!
    Returns a QTime object containing a time \a s seconds later
    than the time of this object (or earlier if \a s is negative).

    Note that the time will wrap if it passes midnight.

    Example:

    \code
        QTime n(14, 0, 0);                // n == 14:00:00
        QTime t;
        t = n.addSecs(70);                // t == 14:01:10
        t = n.addSecs(-70);               // t == 13:58:50
        t = n.addSecs(10 * 60 * 60 + 5);  // t == 00:00:05
        t = n.addSecs(-15 * 60 * 60);     // t == 23:00:00
    \endcode

    \sa addMSecs(), secsTo(), QDateTime::addSecs()
*/

QTime QTime::addSecs(int s) const
{
    return addMSecs(s * 1000);
}

/*!
    Returns the number of seconds from this time to \a t.
    If \a t is earlier than this time, the number of seconds returned
    is negative.

    Because QTime measures time within a day and there are 86400
    seconds in a day, the result is always between -86400 and 86400.

    \sa addSecs(), QDateTime::secsTo()
*/

int QTime::secsTo(const QTime &t) const
{
    return (t.ds() - ds()) / 1000;
}

/*!
    Returns a QTime object containing a time \a ms milliseconds later
    than the time of this object (or earlier if \a ms is negative).

    Note that the time will wrap if it passes midnight. See addSecs()
    for an example.

    \sa addSecs(), msecsTo()
*/

QTime QTime::addMSecs(int ms) const
{
    QTime t;
    if (ms < 0) {
        // % not well-defined for -ve, but / is.
        int negdays = (MSECS_PER_DAY - ms) / MSECS_PER_DAY;
        t.mds = (ds() + ms + negdays * MSECS_PER_DAY) % MSECS_PER_DAY;
    } else {
        t.mds = (ds() + ms) % MSECS_PER_DAY;
    }
    return t;
}

/*!
    Returns the number of milliseconds from this time to \a t.
    If \a t is earlier than this time, the number of milliseconds returned
    is negative.

    Because QTime measures time within a day and there are 86400
    seconds in a day, the result is always between -86400000 and
    86400000 ms.

    \sa secsTo(), addMSecs()
*/

int QTime::msecsTo(const QTime &t) const
{
    return t.ds() - ds();
}


/*!
    \fn bool QTime::operator==(const QTime &t) const

    Returns true if this time is equal to \a t; otherwise returns false.
*/

/*!
    \fn bool QTime::operator!=(const QTime &t) const

    Returns true if this time is different from \a t; otherwise returns false.
*/

/*!
    \fn bool QTime::operator<(const QTime &t) const

    Returns true if this time is earlier than \a t; otherwise returns false.
*/

/*!
    \fn bool QTime::operator<=(const QTime &t) const

    Returns true if this time is earlier than or equal to \a t;
    otherwise returns false.
*/

/*!
    \fn bool QTime::operator>(const QTime &t) const

    Returns true if this time is later than \a t; otherwise returns false.
*/

/*!
    \fn bool QTime::operator>=(const QTime &t) const

    Returns true if this time is later than or equal to \a t;
    otherwise returns false.
*/

/*!
    \overload

    Returns the current time as reported by the system clock.

    Note that the accuracy depends on the accuracy of the underlying
    operating system; not all systems provide 1-millisecond accuracy.
*/

QTime QTime::currentTime()
{
    QTime ct;

#if defined(Q_OS_WIN)
    SYSTEMTIME st;
    memset(&st, 0, sizeof(SYSTEMTIME));
    GetLocalTime(&st);
    ct.mds = MSECS_PER_HOUR * st.wHour + MSECS_PER_MIN * st.wMinute + 1000 * st.wSecond
             + st.wMilliseconds;
#elif defined(Q_OS_UNIX)
    // posix compliant system
    struct timeval tv;
    gettimeofday(&tv, 0);
    time_t ltime = tv.tv_sec;
    tm *t;

#if !defined(QT_NO_THREAD) && defined(_POSIX_THREAD_SAFE_FUNCTIONS)
    // use the reentrant version of localtime() where available
    tm res;
    t = localtime_r(&ltime, &res);
#else
    t = localtime(&ltime);
#endif

    ct.mds = MSECS_PER_HOUR * t->tm_hour + MSECS_PER_MIN * t->tm_min + 1000 * t->tm_sec
             + tv.tv_usec / 1000;
#else
    time_t ltime; // no millisecond resolution
    ::time(&ltime);
    tm *t;
    localtime(&ltime);
    ct.mds = MSECS_PER_HOUR * t->tm_hour + MSECS_PER_MIN * t->tm_min + 1000 * t->tm_sec;
#endif
    return ct;
}

#ifndef QT_NO_DATESTRING
/*!
    \fn QTime QTime::fromString(const QString &string, Qt::DateFormat format)

    Returns the time represented in the \a string as a QTime using the
    \a format given, or an invalid time if this is not possible.

    \warning Note that Qt::LocalDate cannot be used here.
*/
QTime QTime::fromString(const QString& s, Qt::DateFormat f)
{
    if (s.isEmpty() || f == Qt::LocalDate) {
        qWarning("QTime::fromString: Parameter out of range");
        QTime t;
        t.mds = NullTime;
        return t;
    }

    const int hour(s.mid(0, 2).toInt());
    const int minute(s.mid(3, 2).toInt());
    const int second(s.mid(6, 2).toInt());

    const QString msec_s(QLatin1String("0.") + s.mid(9, 4));
    const float msec(msec_s.toFloat());
    return QTime(hour, minute, second, qMin(qRound(msec * 1000.0), 999));
}

/*!
    \fn QTime::fromString(const QString &string, const QString &format)

    Returns the QTime represented by the \a string, using the \a
    format given, or an invalid time if the string cannot be parsed.

    These expressions may be used for the format:

    \table
    \header \i Expression \i Output
    \row \i h
         \i the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
    \row \i hh
         \i the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
    \row \i m \i the minute without a leading zero (0 to 59)
    \row \i mm \i the minute with a leading zero (00 to 59)
    \row \i s \i the second without a leading zero (0 to 59)
    \row \i ss \i the second with a leading zero (00 to 59)
    \row \i z \i the milliseconds without leading zeroes (0 to 999)
    \row \i zzz \i the milliseconds with leading zeroes (000 to 999)
    \row \i AP
         \i interpret as an AM/PM time. \e AP must be either "AM" or "PM".
    \row \i ap
         \i Interpret as an AM/PM time. \e ap must be either "am" or "pm".
    \endtable

    All other input characters will be treated as text. Any sequence
    of characters that are enclosed in single quotes will also be
    treated as text and not be used as an expression.

    \code
        QTime time = QTime::fromString("1mm12car00", "m'mm'hcarss");
        // time is 12:01.00
    \endcode

    If the format is not satisfied an invalid QTime is returned.
    Expressions that do not expect leading zeroes to be given (h, m, s
    and z) are greedy. This means that they will use two digits even if
    this puts them outside the range of accepted values and leaves too
    few digits for other sections. For example, the following string
    could have meant 00:07:10, but the m will grab two digits, resulting
    in an invalid time:

    \code
        QTime time = QTime::fromString("00:710", "hh:ms"); // invalid
    \endcode

    Any field that is not represented in the format will be set to zero.
    For example:

    \code
        QTime time = QTime::fromString("1.30", "m.s");
        // time is 00:01:30.000
    \endcode

    \sa QDateTime::fromString() QDate::fromString() QDate::toString()
    QDateTime::toString() QTime::toString()
*/

QTime QTime::fromString(const QString &string, const QString &format)
{
    QTime time;
#ifndef QT_BOOTSTRAPPED
    QDateTimeParser dt(QVariant::Time);
    if (dt.parseFormat(format))
        dt.fromString(string, 0, &time);
#else
    Q_UNUSED(string);
    Q_UNUSED(format);
#endif
    return time;
}

#endif // QT_NO_DATESTRING


/*!
    \overload

    Returns true if the specified time is valid; otherwise returns
    false.

    The time is valid if \a h is in the range 0 to 23, \a m and
    \a s are in the range 0 to 59, and \a ms is in the range 0 to 999.

    Example:

    \code
        QTime::isValid(21, 10, 30); // returns true
        QTime::isValid(22, 5,  62); // returns false
    \endcode
*/

bool QTime::isValid(int h, int m, int s, int ms)
{
    return (uint)h < 24 && (uint)m < 60 && (uint)s < 60 && (uint)ms < 1000;
}


/*!
    Sets this time to the current time. This is practical for timing:

    \code
        QTime t;
        t.start();
        some_lengthy_task();
        qDebug("Time elapsed: %d ms", t.elapsed());
    \endcode

    \sa restart(), elapsed(), currentTime()
*/

void QTime::start()
{
    *this = currentTime();
}

/*!
    Sets this time to the current time and returns the number of
    milliseconds that have elapsed since the last time start() or
    restart() was called.

    This function is guaranteed to be atomic and is thus very handy
    for repeated measurements. Call start() to start the first
    measurement, and restart() for each later measurement.

    Note that the counter wraps to zero 24 hours after the last call
    to start() or restart().

    \warning If the system's clock setting has been changed since the
    last time start() or restart() was called, the result is
    undefined. This can happen when daylight savings time is turned on
    or off.

    \sa start(), elapsed(), currentTime()
*/

int QTime::restart()
{
    QTime t = currentTime();
    int n = msecsTo(t);
    if (n < 0)                                // passed midnight
        n += 86400*1000;
    *this = t;
    return n;
}

/*!
    Returns the number of milliseconds that have elapsed since the
    last time start() or restart() was called.

    Note that the counter wraps to zero 24 hours after the last call
    to start() or restart.

    Note that the accuracy depends on the accuracy of the underlying
    operating system; not all systems provide 1-millisecond accuracy.

    \warning If the system's clock setting has been changed since the
    last time start() or restart() was called, the result is
    undefined. This can happen when daylight savings time is turned on
    or off.

    \sa start(), restart()
*/

int QTime::elapsed() const
{
    int n = msecsTo(currentTime());
    if (n < 0)                                // passed midnight
        n += 86400 * 1000;
    return n;
}


/*****************************************************************************
  QDateTime member functions
 *****************************************************************************/

/*!
    \class QDateTime
    \reentrant
    \brief The QDateTime class provides date and time functions.

    \ingroup time
    \mainclass

    A QDateTime object contains a calendar date and a clock time (a
    "datetime"). It is a combination of the QDate and QTime classes.
    It can read the current datetime from the system clock. It
    provides functions for comparing datetimes and for manipulating a
    datetime by adding a number of seconds, days, months, or years.

    A QDateTime object is typically created either by giving a date
    and time explicitly in the constructor, or by using the static
    function currentDateTime() that returns a QDateTime object set
    to the system clock's time. The date and time can be changed with
    setDate() and setTime(). A datetime can also be set using the
    setTime_t() function that takes a POSIX-standard "number of
    seconds since 00:00:00 on January 1, 1970" value. The fromString()