就业培训     下载中心     Wiki     联络 登录   注册

---

比较

A maxon::UniversalDateTime can be compared by using standard operators:

• maxon::UniversalDateTime::operator==() : compares two UniversalDateTime used in expression checking values for equality;
• maxon::UniversalDateTime::operator<() : compares two UniversalDateTime used in expression checking the first being smaller than the second.

// allocate and initialize a UniversalDateTime const UInt64 timestamp = 1467363600; const maxon::UniversalDateTime udt = maxon::UniversalDateTime::FromUnixTimestamp (timestamp);

// clone into a new UniversalDateTime const maxon::UniversalDateTime udtCloned(udt);

// allocate and initialize a UniversalDateTime with a slightly different unix timestamp const maxon::UniversalDateTime udtPast = maxon::UniversalDateTime::FromUnixTimestamp (1467363600 - 1);

// compare the initial with the clone if (udt == udtCloned) { // the two instances are equal // do something here DiagnosticOutput ( "udt and udtCloned are equal." ); }

// compare the initial with the clone if (udtPast < udt) { // the first instance is smaller than the second // do something here DiagnosticOutput ( "udtPast refers to a previous date than udt." ); }

注意

From the above operators all the remaining operators (!=, >, >=, <=) are derived and can thus be used as usual.

Conversion

A maxon::UniversalDateTime can be converted to maxon::LocalDateTime using:

• maxon::UniversalDateTime::ConvertToLocalDateTime() : converts to maxon::LocalDateTime using the current time zone;
• maxon::UniversalDateTime::ConvertToLocalDateTime(const TimeValue& utcOffset, DST dst) const : converts to maxon::RemoteDateTime given a time offset and the DST information.

// allocate a UniversalDateTime and initialize to the current time stamp const maxon::UniversalDateTime udtNow = maxon::UniversalDateTime::GetNow ();

// convert, in the current timezone, the UniversalDateTime to a LocalDateTime const maxon::LocalDateTime localNow_currentTZ = udtNow. ConvertToLocalDateTime ();

// allocate and initialize a TimeValue maxon::TimeValue timeoffset; timeoffset. SetHours (2.0);

// allocate and initialize a maxon::DST const maxon::DST dstFlag( maxon::DST::SET );

// convert the UniversalDateTime to a RemoteDateTime using the specified offset and the DST information const maxon::RemoteDateTime remoteNow_offsetDST = udtNow. ConvertToLocalDateTime (timeoffset, dstFlag);

Similarly the following methods return maxon::String representations of the maxon::UniversalDateTime via:

• maxon::UniversalDateTime::FormatTime() : returns a customizable maxon::String based on the given string format used;
• maxon::UniversalDateTime::ToString() : returns a maxon::String representation of the maxon::UniversalDateTime 对象。

注意

maxon::UniversalDateTime::FormatTime() uses the same formatting specified in C++ strftime() function.

// allocate and initialize a UniversalDateTime object const UInt64 timestamp = 1467363600; const maxon::UniversalDateTime udt = maxon::UniversalDateTime::FromUnixTimestamp (timestamp);

// extract useful strings to represent the given timestamp const maxon::String dayOfTheTS = udt. FormatTime ( "%A the %j-th day of year %Y" ); const maxon::String weekOfTheTS = udt. FormatTime ( "the date %d/%m/%Y is in %W-th week" ); const maxon::String timeOfTS = udt. FormatTime ( "the time set is %I:%M:%S %p" ); DiagnosticOutput ( "The unix timestamp [@], refers to @, @, and @." , timestamp, dayOfTheTS, weekOfTheTS, timeOfTS);

Utilities

A few helpful methods are provided with the maxon::UniversalDateTime as utilities:

• maxon::UniversalDateTime::Reset() : reset all values to zero;
• maxon::UniversalDateTime::GetJulianDay() : given the Julian Date variant, returns the Julian day representation of the maxon::UniversalDateTime object;
• maxon::UniversalDateTime::GetUnixTimestamp() : returns the Unix time stamp representation of the maxon::UniversalDateTime object;
• maxon::UniversalDateTime::IsValid() : checks it the maxon::UniversalDateTime object has a time stamp not equal to zero;
• maxon::UniversalDateTime::GetHashCode() : returns the hash code of the maxon::UniversalDateTime 对象。

注意

The Julian day variants have been introduced across the years to adapt to different reference epoch and return a proper Julian day representation of a given time/date. See Variants in Julian day ;

// allocate and initialize an UniversalDateTime at the current timestamp maxon::UniversalDateTime udtNow = maxon::UniversalDateTime::GetNow ();

// convert to the Julian day representation using a legacy variant const maxon::Float jday = udtNow. GetJulianDay ( maxon::JULIANDATE::LEGACY );

// convert to the unix timestamp const maxon::UInt64 tstamp = udtNow. GetUnixTimestamp ();

// retrieve the hash code representation const maxon::UInt udtHC = udtNow. GetHashCode ();

// check the UniversalDateTime's validity if (udtNow. IsValid ()) { // if valid just reset it udtNow. 重置 (); } DiagnosticOutput ( "udtNow has been reset to @" , udtNow);

Finally a Julian day can be obtained using:

• maxon::UniversalDateTime::ToJulianDay() : given the Julian Date variant, year, month, day, hours, minutes and second returns the corresponding Julian day value.

// set the required parameters const JULIANDATE var = maxon::JULIANDATE::STANDARD ; const Int32 year = 2016; const UChar month = 7; const UChar day = 1; const UChar hour = 9; const UChar min = 0; const UChar sec = 0;

// compute the Julian day const maxon::Float64 julianDay = maxon::UniversalDateTime::ToJulianDay (var, year, month, day, hour, min, sec);

// prepare the string representation of the Julian day variant maxon::String varStr; switch (var) { case maxon::JULIANDATE::DUBLIN : varStr = "Dublin" _s; break ; case maxon::JULIANDATE::LEGACY : varStr = "Legacy" _s; break ; case maxon::JULIANDATE::LILIAN : varStr = "Lilian" _s; break ; case maxon::JULIANDATE::MARSSOL : varStr = "Mars Sol" _s; break ; case maxon::JULIANDATE::MODIFIED : varStr = "Modified" _s; break ; case maxon::JULIANDATE::RATEDIE : varStr = "Rata die" _s; break ; case maxon::JULIANDATE::REDUCED : varStr = "Reduced" _s; break ; case maxon::JULIANDATE::STANDARD : varStr = "Standard" _s; break ; }

// show the result DiagnosticOutput (diagIDString + "On date @/@/@ and time @:@:@ , the Julian day computed using the @ variant is @." , day, month, year, hour, min, sec, varStr, julianDay);

A maxon::UniversalDateTime object can be read from and written to disk by serializing the data contained using the conventional functions.

// allocate and initialize a UniversalDateTime const maxon::UniversalDateTime savedUDT = maxon::UniversalDateTime::GetNow ();

// allocate a file URL const maxon::Url url = (targetFolder + "universaldatetime.txt" _s) iferr_return ; const maxon::Id fileID { "net.maxonexample.universaldatetime" };

// save to file maxon::WriteDocument (url, maxon::OPENSTREAMFLAGS::NONE , fileID, savedUDT, maxon::IOFORMAT::JSON ) iferr_return ;

// read back from file maxon::UniversalDateTime loadedUDT; maxon::ReadDocument (url, fileID, loadedUDT) iferr_return ;

延伸阅读

• 数据 & 算法
• Time-based Types
• TimeValue Manual
• DescribeIO Manual