Strange behavior with CDateTimeCtrl

This is a discussion on Strange behavior with CDateTimeCtrl within the Windows Programming forums, part of the Platform Specific Boards category; I'm using MSVC++ 6 in Windows XP Pro SP2, and trying to write a simple dialog with a date/time picker ...

  1. #1
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    May 2004
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    Strange behavior with CDateTimeCtrl

    I'm using MSVC++ 6 in Windows XP Pro SP2, and trying to write a simple dialog with a date/time picker control, and am experiencing some strange behavior; when I try to UpdateData() after entering a time in the control, the last assertion in the following CTime constructor fails, even though all input fields appear valid:
    Code:
    CTime::CTime(int nYear, int nMonth, int nDay, int nHour, int nMin, int nSec, int nDST)
    In particular, this assertion fails for any time earlier than 6 PM. I suspected that my time zone setting might be influencing the problem, so I set my time zone to GMT, and indeed the error vanished.
    Obviously I can't insist my users set their time zone to GMT before running my program - is there something obvious I've missed? Are my MFC source files simply outdated, and if so, is a new version freely available? Thanks for your help.

  2. #2
    the hat of redundancy hat nvoigt's Avatar
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    Can you post the constructor code up to the assertion that failed and your call of said constructor please ?
    hth
    -nv

    She was so Blonde, she spent 20 minutes looking at the orange juice can because it said "Concentrate."

    When in doubt, read the FAQ.
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  3. #3
    Registered User
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    Certainly.

    The constructor code:
    Code:
    CTime::CTime(int nYear, int nMonth, int nDay, int nHour, int nMin, int nSec, int nDST)
    {
    struct tm atm;
    atm.tm_sec = nSec;
    atm.tm_min = nMin;
    atm.tm_hour = nHour;
    ASSERT(nDay >= 1 && nDay <= 31);
    atm.tm_mday = nDay;
    ASSERT(nMonth >= 1 && nMonth <= 12);
    atm.tm_mon = nMonth -1; // tm_mon is 0 based
    ASSERT(nYear >= 1900);
    atm.tm_year = nYear - 1900; //tm_year is 1900 based
    atm.tm_isdst = nDST;
    m_time = mktime(&atm);
    ASSERT(m_time != -1); //This assertion fails
    }
    The above is called from the following other CTime constructor:
    Code:
    CTime::CTime(const SYSTEMTIME& sysTime, int nDST)
    {
    if(sysTime.wYear < 1900)
    {
         time_t time0 = 0L;
         CTime timeT(time0);
         *this = timeT;
    }
    else
    {
         //This next line calls the constructor with failed assertion
         CTime timeT( (int)sysTime.wYear, (int)sysTime.wMonth, (int)sysTime.wDay, (int)sysTime.wHour, (int)sysTime.wMinute, (int)sysTime.wSecond, nDST);
         *this = timeT;
    }
    }
    which in turn is called by

    Code:
    DWORD CDateTimeCtrl::GetTime(CTime& timeDest) const
    {
         SYSTEMTIME sysTime;
         DWORD dwResult = (DWORD)
                   ::SendMessage(m_hWnd, DTM_GETSYSTEMTIME, 0, (LPARAM) &sysTime);
    
         if (dwResult == GDT_VALID)
             timeDest = CTime(sysTime); //Execution flow goes through here
    
        return dwResult;
    }
    Note that all of the above is stock MFC code; the only thing I do is call UpdateData(), which calls DoDataExchange, which calls the above.

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