MFC: COleDateTime vs. CTime. Which one is better?
Q: There are two MFC/ATL classes that encapsulate date and time: COleDateTime and CTime. Which one is better?
A: Next are few arguments to prefer COleDateTime instead of CTime:
- CTime keeps date between January 1, 1970 and December 31, 3000 (January 19, 2038 in older implementations). That is not enugh for most applications. For example, in a database may be persons born before 1970.
COleDateTime can handle date between January 1, 100 and December 31, 9999 which is pretty much better.
Example
Code:
// my birth date is
CTime t(1961, 8, 17); // August 17, 1961
CString strMyBirthDate = t.Format(_T("%m/%d/%Y"));
// results "01/08/1984"; I would like it to be truw, but it's not. :)
COleDateTime odt(1961, 8, 17, 0, 0, 0);
strMyBirthDate = odt.Format(_T("%m/%d/%Y"));
// results "08/17/1961", which is correct
- COleDateTime has more powerful, flexible and easier to use Format functions, while CTime is limited to Format functins taking formatting specifiers.
Example
Code:
CTime t(2007, 9, 11, 8, 25, 55);
// hard-coded date-time format (may be German)
CString strDateTime = t.Format(_T("%d.%m.%Y %H:%M:%S"));
// what about if English US, or Japanese, or another format is required at a moment?
// that's no sweat, by using COleDateTime:
COleDateTime odt(2007, 9, 11, 8, 25, 55);
LCID lcid = 0x409; // 0x409 is the locale ID for English US
strDateTime = odt.Format(0, lcid);
// and it's even easier if want to format according to user language set in Control Panel:
strDateTime = odt.Format();
- COleDateTime has a ParseDateTime function while CTime has not.
Example
Code:
COleDateTime odt;
// set odt value given a date-time string
odt.ParseDateTime(_T("9/12/2007 2:48:17 PM"), 0, 0x409);
// CTime has not such a member function
- COleDateTime has Set functions (SetDate and SetDateTime) while CTime has not.
Example
Code:
COleDateTime odt(2007, 10, 10, 0, 0, 0);
// sets a new value using SetDateTime:
odt.SetDateTime(2008, 11, 11, 11, 11, 11);
CTime t(2007, 10, 10, 0, 0, 0);
// sets a new value assigning a temporary CTime object, like dancing on the rope. :)
t = CTime(2008, 11, 11, 11, 11, 11);
- COleDateTime is more precise when dealing with relative time periods.
Example
Code:
COleDateTime odt(1970, 9, 30, 0, 0, 0);
odt += COleDateTimeSpan(31, 0, 0, 0);
CString strTime1 = odt.Format(_T("%d.%m.%Y %H:%M:%S"));
// results "31.10.1970 00:00:00" which is correct
CTime t(1970, 9, 30, 0, 0, 0);
t += CTimeSpan(31, 0, 0, 0);
CString strTime2 = t.Format(_T("%d.%m.%Y %H:%M:%S"));
// results "30.10.1970 23:00:00"
// one hour is missing, jumping back in the previous day
Additional notes:
- In actual implementation, CTime, CTimeSpan, COleDateTime and COleDateTimeSpan are shared by MFC and ATL libraries, so can be easily used both in MFC and non-MFC applications.
See also
