如何将QByteArray存放的十六进制源码数据转换为时间信息（QDateTime）?
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如何将QByteArray存放的十六进制源码数据转换为时间信息（QDateTime）?
[问题点数：40分，结帖人suifeng3702]
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本帖子已过去太久远了，不再提供回复功能。QDateTime Class | Qt 4.8
QDateTime Class
class provides date and time functions.
Header: #include &QDateTime&
Note: All functions in this class are .
Public Functions
(const QDate & date)
(const QDate & date, const QTime & time, Qt::TimeSpec spec = Qt::LocalTime)
(const QDateTime & other)
QDateTime (int ndays) const
QDateTime (qint64 msecs) const
QDateTime (int nmonths) const
QDateTime (int s) const
QDateTime (int nyears) const
QDate () const
int (const QDateTime & other) const
bool () const
bool () const
qint64 (const QDateTime & other) const
int (const QDateTime & other) const
void (const QDate & date)
void (qint64 msecs)
void (const QTime & time)
void (Qt::TimeSpec spec)
void (uint seconds)
QTime () const
Qt::TimeSpec () const
QDateTime () const
qint64 () const
QString (const QString & format) const
QString (Qt::DateFormat format = Qt::TextDate) const
QDateTime (Qt::TimeSpec specification) const
uint () const
QDateTime () const
bool (const QDateTime & other) const
bool (const QDateTime & other) const
bool (const QDateTime & other) const
QDateTime & (const QDateTime & other)
bool (const QDateTime & other) const
bool (const QDateTime & other) const
bool (const QDateTime & other) const
Static Public Members
QDateTime ()
QDateTime ()
QDateTime (qint64 msecs)
QDateTime (const QString & string, Qt::DateFormat format = Qt::TextDate)
QDateTime (const QString & string, const QString & format)
QDateTime (uint seconds)
Related Non-Members
QDataStream & (QDataStream & out, const QDateTime & dateTime)
QDataStream & (QDataStream & in, QDateTime & dateTime)
Detailed Description
class provides date and time functions.
object contains a calendar date and a clock time (a &datetime&). It is a combination of the
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.
object is typically created either by giving a date and time explicitly in the constructor, or by using the static function () that returns a
object set to the system clock's time. The date and time can be changed with () and (). A datetime can also be set using the () function that takes a POSIX-standard &number of seconds since 00:00:00 on January 1, 1970& value. The () function returns a , given a string and a date format used to interpret the date within the string.
The () and () functions provide access to the date and time parts of the datetime. The same information is provided in textual format by the () function.
provides a full set of operators to compare two
objects where smaller means earlier and larger means later.
You can increment (or decrement) a datetime by a given number of milliseconds using (), seconds using (), or days using (). Similarly you can use () and (). The () function returns the number of days between two datetimes, () returns the number of seconds between two datetimes, and () returns the number of milliseconds between two datetimes.
can store datetimes as
or as . () returns a
exp use () to convert it to UTC. You can also use () to find out if a
object stores a UTC time or a local time. Operations such as () and () are aware of daylight saving time (DST).
does not account for leap seconds.
Use of Gregorian and Julian Calendars
uses the Gregorian calendar in all locales, beginning on the date 15 October 1582. For dates up to and including 4 October 1582, the Julian calendar is used. This means there is a 10-day gap in the internal calendar between the 4th and the 15th of October 1582. When you use
for dates in that epoch, the day after 4 October 1582 is 15 October 1582, and the dates in the gap are invalid.
The Julian to Gregorian changeover date used here is the date when the Gregorian calendar was first introduced, by Pope Gregory XIII. That change was not universally accepted and some localities only executed it at a later date (if at all).
doesn't take any of these historical facts into account. If an application must support a locale-specific dating system, it must do so on its own, remembering to convert the dates using the Julian day.
There is no year 0. Dates in that year are considered invalid. The year -1 is the year &1 before Christ& or &1 before current era.& The day before
is December 31st, 1 BCE.
Range of Valid Dates
The range of valid dates is from January 2nd, 4713 BCE, to sometime in the year 11 million CE. The Julian Day returned by () is a number in the contiguous range from 1 to overflow, even across 's &date holes&. It is suitable for use in applications that must convert a
to a date in another calendar system, e.g., Hebrew, Islamic or Chinese.
The Gregorian calendar was introduced in different places around the world on different dates.
to store the date, so it uses the Gregorian calendar for all locales, beginning on the date 15 October 1582. For dates up to and including 4 October 1582,
uses the Julian calendar. This means there is a 10-day gap in the
calendar between the 4th and the 15th of October 1582. When you use
for dates in that epoch, the day after 4 October 1582 is 15 October 1582, and the dates in the gap are invalid.
Use of System Timezone
uses the system's time zone information to determine the offset of local time from UTC. If the system is not configured correctly or not up-to-date,
will give wrong results as well.
Daylight Savings Time (DST)
takes into account the system's time zone information when dealing with DST. On modern Unix systems, this means it applies the correct historical DST data whenever possible. On Windows and Windows CE, where the system doesn't support historical DST data, historical accuracy is not maintained with respect to DST.
The range of valid dates taking DST into account is
to the present, and rules are in place for handling DST correctly until , but these could change. For dates falling outside that range,
makes a best guess using the rules for year 1970 or 2037, but we can't guarantee accuracy. This means
doesn't take into account changes in a locale's time zone before 1970, even if the system's time zone database supports that information.
See also , , and .
Member Function Documentation
Constructs a null datetime (i.e. null date and null time). A null datetime is invalid, since the date is invalid.
See also ().
Constructs a datetime with the given date, a valid time(00:00:00.000), and sets the () to .
Constructs a datetime with the given date and time, using the time specification defined by spec.
If date is valid and time is not, the time will be set to midnight.
Constructs a copy of the other datetime.
Destroys the datetime.
QDateTime::addDays(int ndays) const
object containing a datetime ndays days later than the datetime of this object (or earlier if ndays is negative).
See also (), (), (), and ().
QDateTime::addMSecs( msecs) const
object containing a datetime msecs miliseconds later than the datetime of this object (or earlier if msecs is negative).
See also (), (), (), (), and ().
QDateTime::addMonths(int nmonths) const
object containing a datetime nmonths months later than the datetime of this object (or earlier if nmonths is negative).
See also (), (), (), and ().
QDateTime::addSecs(int s) const
object containing a datetime s seconds later than the datetime of this object (or earlier if s is negative).
See also (), (), (), (), and ().
QDateTime::addYears(int nyears) const
object containing a datetime nyears years later than the datetime of this object (or earlier if nyears is negative).
See also (), (), (), and ().
Returns the current datetime, as reported by the system clock, in the local time zone.
See also (), (), (), and ().
Returns the current datetime, as reported by the system clock, in UTC.
This function was introduced in
See also (), (), (), and ().
QDateTime::currentMSecsSinceEpoch()
Returns the number of milliseconds since T00:00:00 Universal Coordinated Time. This number is like the POSIX time_t variable, but expressed in milliseconds instead.
This function was introduced in
See also (), (), (), and ().
Returns the date part of the datetime.
See also (), (), and ().
int QDateTime::daysTo(const
& other) const
Returns the number of days from this datetime to the other datetime. If the other datetime is earlier than this datetime, the value returned is negative.
See also (), (), and ().
QDateTime::fromMSecsSinceEpoch( msecs)
Returns a datetime whose date and time are the number of milliseconds, msecs, that have passed since T00:00:00.000, Coordinated Universal Time (). On systems that do not support time zones, the time will be set as if local time were .
Note that there are possible values for msecs that lie outside the valid range of , both negative and positive. The behavior of this function is undefined for those values.
This function was introduced in
See also () and ().
QDateTime::fromString(const
& string, Qt::DateFormat format = Qt::TextDate)
Returns the
represented by the string, using the format given, or an invalid datetime if this is not possible.
Note for : It is recommended that you use the English short month names (e.g. &Jan&). Although localized month names can also be used, they depend on the user's locale settings.
QDateTime::fromString(const
& string, const
Returns the
represented by the string, using the format given, or an invalid datetime if the string cannot be parsed.
These expressions may be used for the date part of the format string:
ExpressionOutput
dthe day as number without a leading zero (1 to 31)
ddthe day as number with a leading zero (01 to 31)
dddthe abbreviated localized day name (e.g. 'Mon' to 'Sun'). Uses ().
ddddthe long localized day name (e.g. 'Monday' to 'Sunday'). Uses ().
Mthe month as number without a leading zero (1-12)
MMthe month as number with a leading zero (01-12)
MMMthe abbreviated localized month name (e.g. 'Jan' to 'Dec'). Uses ().
MMMMthe long localized month name (e.g. 'January' to 'December'). Uses ().
yythe year as two digit number (00-99)
yyyythe year as four digit number
Note: Unlike the other version of this function, day and month names must be given in the user's local language. It is only possible to use the English names if the user's language is English.These expressions may be used for the time part of the format string:
ExpressionOutput
hthe hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
hhthe hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
Hthe hour without a leading zero (0 to 23, even with AM/PM display)
HHthe hour with a leading zero (00 to 23, even with AM/PM display)
mthe minute without a leading zero (0 to 59)
mmthe minute with a leading zero (00 to 59)
sthe second without a leading zero (0 to 59)
ssthe second with a leading zero (00 to 59)
zthe milliseconds without leading zeroes (0 to 999)
zzzthe milliseconds with leading zeroes (000 to 999)
AP or Ainterpret as an AM/PM time. AP must be either &AM& or &PM&.
ap or aInterpret as an AM/PM time. ap must be either &am& or &pm&.
All other input characters will be treated as text. Any sequence of characters that are enclosed in singlequotes will also be treated as text and not be used as an expression.
time1 = ::(&131&, &HHh&);
time1 = ::(&1apA&, &1amAM&);
dateTime2 = ::(&M1d1y&,
&'M'M'd'd'y'yyhh:mm:ss&);
If the format is not satisfied an invalid
is returned. The expressions that don't have leading zeroes (d, M, h, m, s, z) will be greedy. This means that they will use two digits even if this will put them outside the range and/or leave too few digits for other sections.
dateTime = ::(&130&, &Mm&);
This could have meant 1 January 00:30.00 but the M will grab two digits.
For any field that is not represented in the format the following defaults are used:
FieldDefault value
Month1 (January)
For example:
dateTime = ::(&1.30.1&, &M.d.s&);
See also (), (), and ().
Returns a datetime whose date and time are the number of seconds that have passed since T00:00:00, Coordinated Universal Time (). On systems that do not support time zones, the time will be set as if local time were .
This function was introduced in
See also () and ().
bool QDateTime::isNull() const
Returns true if both the date a otherwise returns false. A null datetime is invalid.
See also (), (), and ().
bool QDateTime::isValid() const
Returns true if both the date an otherwise returns false.
See also () and ().
QDateTime::msecsTo(const
& other) const
Returns the number of milliseconds from this datetime to the other datetime. If the other datetime is earlier than this datetime, the value returned is negative.
Before performing the comparison, the two datetimes are converted to
to ensure that the result is correct if one of the two datetimes has daylight saving time (DST) and the other doesn't.
This function was introduced in
See also (), (), and ().
int QDateTime::secsTo(const
& other) const
Returns the number of seconds from this datetime to the other datetime. If the other datetime is earlier than this datetime, the value returned is negative.
Before performing the comparison, the two datetimes are converted to
to ensure that the result is correct if one of the two datetimes has daylight saving time (DST) and the other doesn't.
now = ::();
xmas((now.date().year(), 12, 25), (0, 0));
(&There are %d seconds to Christmas&, now.secsTo(xmas));
See also (), (), and ().
Sets the date part of this datetime to date. If no time is set, it is set to midnight.
See also (), (), and ().
void QDateTime::setMSecsSinceEpoch( msecs)
Sets the date and time given the number of milliseconds,msecs, that have passed since T00:00:00.000, Coordinated Universal Time (). On systems that do not support time zones this function will behave as if local time were .
Note that there are possible values for msecs that lie outside the valid range of , both negative and positive. The behavior of this function is undefined for those values.
This function was introduced in
See also () and ().
Sets the time part of this datetime to time.
See also (), (), and ().
Sets the time specification used in this datetime to spec.
See also (), (), (), and .
Sets the date and time given the number of seconds that have passed since T00:00:00, Coordinated Universal Time (). On systems that do not support time zones this function will behave as if local time were .
See also ().
Returns the time part of the datetime.
See also (), (), and ().
Returns the time specification of the datetime.
See also (), (), (), and .
Returns a datetime containing the date and time information in this datetime, but specified using the
definition.
See also ().
QDateTime::toMSecsSinceEpoch() const
Returns the datetime as the number of milliseconds that have passed since T00:00:00.000, Coordinated Universal Time ().
On systems that do not support time zones, this function will behave as if local time were .
The behavior for this function is undefined if the datetime stored in this object is not valid. However, for all valid dates, this function returns a unique value.
This function was introduced in
See also () and ().
QDateTime::toString(const
& format) const
Returns the datetime as a string. The format parameter determines the format of the result string.
These expressions may be used for the date:
ExpressionOutput
dthe day as number without a leading zero (1 to 31)
ddthe day as number with a leading zero (01 to 31)
dddthe abbreviated localized day name (e.g. 'Mon' to 'Sun'). Uses ().
ddddthe long localized day name (e.g. 'Monday' to ''). Uses ().
Mthe month as number without a leading zero (1-12)
MMthe month as number with a leading zero (01-12)
MMMthe abbreviated localized month name (e.g. 'Jan' to 'Dec'). Uses ().
MMMMthe long localized month name (e.g. 'January' to 'December'). Uses ().
yythe year as two digit number (00-99)
yyyythe year as four digit number
These expressions may be used for the time:
ExpressionOutput
hthe hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
hhthe hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
mthe minute without a leading zero (0 to 59)
mmthe minute with a leading zero (00 to 59)
sthe second without a leading zero (0 to 59)
ssthe second with a leading zero (00 to 59)
zthe milliseconds without leading zeroes (0 to 999)
zzzthe milliseconds with leading zeroes (000 to 999)
APuse AM/PM display. AP will be replaced by either &AM& or &PM&.
apuse am/pm display. ap will be replaced by either &am& or &pm&.
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 (assumed that the
is 21 May :09):
FormatResult
dd.MM.yyyy21.05.2001
ddd MMMM d yyTue May 21 01
hh:mm:ss.zzz14:13:09.042
h:m:s ap2:13:9 pm
If the datetime is invalid, an empty string will be returned.
See also () and ().
QDateTime::toString(Qt::DateFormat format = Qt::TextDate) const
This is an overloaded function.
Returns the datetime as a string in the format given.
If the format is , the string is formatted in the default way. (), (), and () are used to generate the string, so the day and month names will be localized names. An example of this formatting is &Wed May 20 03:40:13 1998&.
If the format is , the string format corresponds to the ISO 8601 extended specification for representations of dates and times, taking the form YYYY-MM-DDTHH:mm:ss[Z|[+|-]HH:mm], depending on the () of the . If the () is , Z will be ap if the () is
the offset in hours and minutes from UTC will be appended to the string.
If the format is
or , the string format depends on the locale settings of the system. Identical to calling ().(datetime, ) or ().(datetime, ).
If the format is
or , the string format depends on the default application locale. This is the locale set with (), or the system locale if no default locale has been set. Identical to calling QLocale().(datetime, ) or QLocale().(datetime, ).
If the datetime is invalid, an empty string will be returned.
Warning: The
format is only valid for years in the range 0 to 9999. This restriction may apply to locale-aware formats as well, depending on the locale settings.
See also (), (), and .
Returns a copy of this datetime configured to use the given time specification.
See also (), (), and ().
Returns the datetime as the number of seconds that have passed since T00:00:00, Coordinated Universal Time ().
On systems that do not support time zones, this function will behave as if local time were .
Note: This function returns a 32-bit unsigned integer, so it does not support dates before 1970, but it does support dates after T03:14:06, which may not be valid time_t values. Be careful when passing those time_t values to system functions, which could interpret them as negative dates.If the date is outside the range T00:00:00 to T06:28:14, this function returns -1 cast to an unsigned integer (i.e., 0xFFFFFFFF).
To get an extended range, use ().
See also () and ().
QDateTime::toUTC() const
Returns a datetime containing the date and time information in this datetime, but specified using the
definition.
See also ().
bool QDateTime::operator!=(const
& other) const
Returns true if this datetime is different from the other otherwise returns false.
Two datetimes are different if either the date, the time, or the time zone components are different.
See also ().
bool QDateTime::operator&(const
& other) const
Returns true if this datetime is earlier than the other otherwise returns false.
bool QDateTime::operator&=(const
& other) const
Returns true if this datetime is earlier than or equal to the other otherwise returns false.
& QDateTime::operator=(const
Makes a copy of the other datetime and returns a reference to the copy.
bool QDateTime::operator==(const
& other) const
Returns true if this datetime is equal to the other otherwise returns false.
See also ().
bool QDateTime::operator&(const
& other) const
Returns true if this datetime is later than the other otherwise returns false.
bool QDateTime::operator&=(const
& other) const
Returns true if this datetime is later than or equal to the other otherwise returns false.
Related Non-Members
& operator&&( & out, const
& dateTime)
Writes dateTime to the out stream.
See also .
& operator&&( & in,
& dateTime)
Reads a datetime from the stream in into dateTime.
See also .
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