qdatetime.cpp

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	y += 1900;
    else if ( y < FIRST_YEAR || (y == FIRST_YEAR && (m < 9 ||
						    (m == 9 && d < 14))) )
	return FALSE;
    return (d > 0 && m > 0 && m <= 12) &&
	   (d <= monthDays[m] || (d == 29 && m == 2 && leapYear(y)));
}

/*!
  Returns TRUE if the specified year \a y is a leap year.
*/

bool QDate::leapYear( int y )
{
    return y % 4 == 0 && y % 100 != 0 || y % 400 == 0;
}

/*!
  \internal
  Converts a Gregorian date to a Julian day.
  This algorithm is taken from Communications of the ACM, Vol 6, No 8.
  \sa jul2greg()
*/

uint QDate::greg2jul( int y, int m, int d )
{
    uint c, ya;
    if ( y <= 99 )
	y += 1900;
    if ( m > 2 ) {
	m -= 3;
    } else {
	m += 9;
	y--;
    }
    c = y;					// NOTE: Sym C++ 6.0 bug
    c /= 100;
    ya = y - 100*c;
    return 1721119 + d + (146097*c)/4 + (1461*ya)/4 + (153*m+2)/5;
}

/*!
  \internal
  Converts a Julian day to a Gregorian date.
  This algorithm is taken from Communications of the ACM, Vol 6, No 8.
  \sa greg2jul()
*/

void QDate::jul2greg( uint jd, int &y, int &m, int &d )
{
    uint x;
    uint j = jd - 1721119;
    y = (j*4 - 1)/146097;
    j = j*4 - 146097*y - 1;
    x = j/4;
    j = (x*4 + 3) / 1461;
    y = 100*y + j;
    x = (x*4) + 3 - 1461*j;
    x = (x + 4)/4;
    m = (5*x - 3)/153;
    x = 5*x - 3 - 153*m;
    d = (x + 5)/5;
    if ( m < 10 ) {
	m += 3;
    } else {
	m -= 9;
	y++;
    }
}


/*****************************************************************************
  QTime member functions
 *****************************************************************************/

/*!
  \class QTime qdatetime.h

  \brief The QTime class provides clock time functions.

  \ingroup time

  A QTime object contains a clock time, i.e. a number of hours,
  minutes, seconds and milliseconds since midnight. It can read the
  current time from the system clock, and measure a span of elapsed
  time. It provides functions for comparing times and for manipulating
  a time by adding a number of (milli)seconds.

  QTime operates with 24-hour clock format; it has no concept of
  AM/PM. It operates with local time; it does not know anything about
  time zones or daylight savings time.

  A QTime object is typically created either by giving the number of
  hours, minutes, seconds, and milliseconds explicitly, or by using
  the static function currentTime(), which makes a QTime object which
  contains the system's clock time. Note that the accuracy depends on
  the accuracy of the underlying operating system; not all systems
  provide 1-millisecond accuracy.

  The hour(), minute(), second(), and msec() functions provide access
  to the number of hours, minutes, seconds, and milliseconds of the
  time. The same information is provided in textual format by the
  toString() function.

  QTime provides a full set of operators to compare two QTime
  objects. A time is considered smaller than another if it is earlier
  than the other.

  The time a given number of seconds or milliseconds later than a
  given time can be found using the addSecs() or addMSecs()
  functions. Correspondingly, the number of (milli)seconds between two
  times can be found using the secsTo() or msecsTo() functions.

  QTime can be used to measure a span of elapsed time using the
  start(), restart(), and elapsed() functions.

  \sa QDate, QDateTime
*/

/*!
  \fn QTime::QTime()

  Constructs the time 0 hours, minutes, seconds and milliseconds,
  i.e. 00:00:00.000 (midnight). This is a valid time.

  \sa isValid()
*/

/*!
  Constructs a time with hour \a h, minute \a m, seconds \a s and
  milliseconds \a ms.

  \a h must be in the range 0-23, \a m and \a s must be in the range
  0-59, and \a ms must be in the range 0-999.

  \sa isValid()
*/

QTime::QTime( int h, int m, int s, int ms )
{
    setHMS( h, m, s, ms );
}


/*!
  \fn bool QTime::isNull() const
  Returns TRUE if the time is equal to 00:00:00.000. A null time is valid.

  \sa isValid()
*/

/*!
  Returns TRUE if the time is valid, or FALSE if the time is invalid.
  The time 23:30:55.746 is valid, while 24:12:30 is invalid.

  \sa isNull()
*/

bool QTime::isValid() const
{
    return ds < MSECS_PER_DAY;
}


/*!
  Returns the hour part (0..23) of the time.
*/

int QTime::hour() const
{
    return ds / MSECS_PER_HOUR;
}

/*!
  Returns the minute part (0..59) of the time.
*/

int QTime::minute() const
{
    return (ds % MSECS_PER_HOUR)/MSECS_PER_MIN;
}

/*!
  Returns the second part (0..59) of the time.
*/

int QTime::second() const
{
    return (ds / 1000)%SECS_PER_MIN;
}

/*!
  Returns the millisecond part (0..999) of the time.
*/

int QTime::msec() const
{
    return ds % 1000;
}


/*!
  Returns the time of this object in a textual format. Milliseconds
  are not included. The string format is HH:MM:SS, e.g. 1 second
  before midnight would be "23:59:59".
*/

QString QTime::toString() const
{
    QString buf;
    buf.sprintf( "%.2d:%.2d:%.2d", hour(), minute(), second() );
    return buf;
}


/*!
  Sets the time to hour \a h, minute \a m, seconds \a s and
  milliseconds \a ms.

  \a h must be in the range 0-23, \a m and \a s must be in the range
  0-59, and \a ms must be in the range 0-999. Returns TRUE if the set
  time is valid, otherwise FALSE.

  \sa isValid()
*/

bool QTime::setHMS( int h, int m, int s, int ms )
{
    if ( !isValid(h,m,s,ms) ) {
#if defined(CHECK_RANGE)
	qWarning( "QTime::setHMS Invalid time %02d:%02d:%02d.%03d", h, m, s,
		 ms );
#endif
	ds = MSECS_PER_DAY;		// make this invalid
	return FALSE;
    }
    ds = (h*SECS_PER_HOUR + m*SECS_PER_MIN + s)*1000 + ms;
    return TRUE;
}

/*!
  Returns a QTime object containing a time \a nsecs seconds later than
  the time of this object (or earlier if \a ms 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 nsecs ) const
{
    return addMSecs(nsecs*1000);
}

/*!
  Returns the number of seconds from this time to \a t (which is
  negative if \a t is earlier than this time).

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

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

int QTime::secsTo( const QTime &t ) const
{
    return ((int)t.ds - (int)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.ds = ((int)ds + ms + negdays*MSECS_PER_DAY)
		% MSECS_PER_DAY;
    } else {
	t.ds = ((int)ds + ms) % MSECS_PER_DAY;
    }
    return t;
}

/*!
  Returns the number of milliseconds from this time to \a t (which is
  negative if \a t is earlier than this time).

  Since QTime measures time within a day and there are 86400000
  milliseconds in a day, the result is between -86400000 and 86400000.

  \sa secsTo()
*/

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


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

  Returns TRUE if this time is equal to \a t, or FALSE if they are
  different.
*/

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

  Returns TRUE if this time is different from \a t, or FALSE if they
  are equal.
*/

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

  Returns TRUE if this time is earlier than \a t, otherwise FALSE.
*/

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

  Returns TRUE if this time is earlier than or equal to \a t,
  otherwise FALSE.
*/

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

  Returns TRUE if this time is later than \a t, otherwise FALSE.
*/

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

  Returns TRUE if this time is later than or equal to \a t, otherwise
  FALSE.
*/



/*!
  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;
    currentTime( &ct );
    return ct;
}

/*!
  \internal

  Fetches the current time and returns TRUE if the time is within one
  minute after midnight, otherwise FALSE. The return value is used by
  QDateTime::currentDateTime() to ensure that the date there is correct.
*/

bool QTime::currentTime( QTime *ct )
{
    if ( !ct ) {
#if defined(CHECK_NULL)
	qWarning( "QTime::currentTime(QTime *): Null pointer not allowed" );
#endif
	return FALSE;
    }

#if defined(_OS_WIN32_)

    SYSTEMTIME t;
    GetLocalTime( &t );
    ct->ds = MSECS_PER_HOUR*t.wHour + MSECS_PER_MIN*t.wMinute +
	     1000*t.wSecond + t.wMilliseconds;
    return (t.wHour == 0 && t.wMinute == 0);

#elif defined(_OS_OS2_)

    DATETIME t;
    DosGetDateTime( &t );
    ct->ds = MSECS_PER_HOUR*t.hours + MSECS_PER_MIN*t.minutes +
	     1000*t.seconds + 10*t.hundredths;
    return (t.hours == 0 && t.minutes == 0);

#elif defined(_OS_MSDOS_)

    _dostime_t t;
    _dos_gettime( &t );
    ct->ds = MSECS_PER_HOUR*t.hour + MSECS_PER_MIN*t.minute +
	     t.second*1000 + t.hsecond*10;
    return (t.hour== 0 && t.minute == 0);

#elif defined(_OS_UNIX_)

    struct timeval tv;
    gettimeofday( &tv, 0 );
    time_t ltime = tv.tv_sec;
    tm *t = localtime( &ltime );
    ct->ds = (uint)( MSECS_PER_HOUR*t->tm_hour + MSECS_PER_MIN*t->tm_min +
		     1000*t->tm_sec + tv.tv_usec/1000 );
    return (t->tm_hour== 0 && t->tm_min == 0);

#else

    time_t ltime;			// no millisecond resolution!!
    ::time( &ltime );
    tm *t = localtime( &ltime );
    ct->ds = MSECS_PER_HOUR*t->tm_hour + MSECS_PER_MIN*t->tm_min +
	     1000*t->tm_sec;
    return (t->tm_hour== 0 && t->tm_min == 0);
#endif
}

/*!
  Returns TRUE if the specified time is valid, otherwise FALSE.

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

  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();				// start clock
    ... // some lengthy task
    qDebug( "%d\n", t.elapsed() );	// prints # msecs 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.