Calendar function crashes when invoking 'localtime_s'

Question

I'm trying to make a callendar, so I use time_t and localtime_s to store the time and date info and then store it in individual members of the Calendar class:

void Callendar::Initialize()
{
    time_t now = time(0);
    tm *localTime = null;
    localtime_s(localTime, &now);

    LocalSeconds = localTime->tm_sec;
    LocalMinutes = localTime->tm_min;
    LocalHours = localTime->tm_hour;
    LocalDays = localTime->tm_mday;
    LocalMonths = localTime->tm_mon;
    LocalYears = localTime->tm_year;
    DaysSinceSunday = localTime->tm_wday;
    DaysSinceJanuaryFirst = localTime->tm_yday;
    HoursDaylightSavings = localTime->tm_isdst;
}

All compiles fine, however at runtime I get:

Debug Assertion Failed!

Program: C:\Users\MyPC\Desktop\Framework\Framework\Debug\Framework.exe File: f:\dd\vctools\crt_bld\self_x86\crt\src\loctim64.c Line: 69

Expression: ( ptm != NULL )

After I close the failed assert message, I get a standart debug error at this line:

static __inline errno_t __CRTDECL localtime_s(struct tm * _Tm, const time_t * _Time)
{
    return _localtime64_s(_Tm, _Time);
}

Which is basically the result of calling *localtime_s(localTime, &now);* in Calendar:Initialize() Could I possibly using a deprecated version of this functionality?I know there are other functions to get localtime, but I don't know which is the "proper" one.Others have suggested to me that I shouldn't use 'localtime', but seemingly localtime_s isn't working out either.

Answer 1

Please see documentation

Parameters

_tm

Pointer to the time structure to be filled in.

Meaning that the function expects the first parameter to be a non null pointer to a valid tm instance.

change

tm *localTime = null;
localtime_s(localTime, &now);

to

tm localTime;
localtime_s(&localTime, &now);

Answer 2

The localtime_s function wants an allocated struct tm pointer, while you pass it a null pointer.

Use e.g.

tm localTime:
localtime_s(&localTime, &now);

Answer 3

ha!

#include <iostream>
#include <fstream>
#include <ctime>
//#include <string>
//#include <cstring>
//#include <sstream>
using namespace std;

int main ()
{

    int LocalSeconds, LocalMinutes,  LocalHours, LocalDays, LocalMonths, LocalYears,
        DaysSinceSunday, DaysSinceJanuaryFirst, HoursDaylightSavings;

    time_t now = time(0);
        tm localTime;
    now = time(NULL); 
    localtime_s(&localTime, &now);


    LocalSeconds = (&localTime)->tm_sec;
    LocalMinutes = (&localTime)->tm_min;
    LocalHours = (&localTime)->tm_hour;
    LocalDays = (&localTime)->tm_mday;
    LocalMonths = (&localTime)->tm_mon;
    LocalYears = (&localTime)->tm_year;
    DaysSinceSunday = (&localTime)->tm_wday;
    DaysSinceJanuaryFirst = (&localTime)->tm_yday;
    HoursDaylightSavings = (&localTime)->tm_isdst;

    cout << LocalSeconds << " " << LocalMinutes<< " " <<  LocalHours<< " " << LocalDays
        << " " << LocalMonths<< " " << LocalYears<< " " <<endl;

    return 0;

}

Answer 4

Happened to be dealing with the same issue recently. To avoid compiler errors/warnings as well, I recommend the following:

tm *localTime = new tm();
localtime_s(localTime, &now);

If you don't initialize localTime you will get an "error C4700: uninitialized local variable 'localTime' used"