Two seperate tm structs mirroring each other
- by BSchlinker
Here is my current situation:
I have two tm structs, both set to the current time
I make a change to the hour in one of the structs
The change is occurring in the other struct magically....
How do I prevent this from occurring? I need to be able to compare and know the number of seconds between two different times -- the current time and a time in the future. I've been using difftime and mktime to determine this. I recognize that I don't technically need two tm structs (the other struct could just be a time_t loaded with raw time) but I'm still interested in understanding why this occurs.
void Tracker::monitor(char* buffer){
// time handling
time_t systemtime, scheduletime, currenttime;
struct tm * dispatchtime;
struct tm * uiuctime;
double remainingtime;
// let's get two structs operating with current time
dispatchtime = dispatchtime_tm();
uiuctime = uiuctime_tm();
// set the scheduled parameters
dispatchtime->tm_hour = 5;
dispatchtime->tm_min = 05;
dispatchtime->tm_sec = 14;
uiuctime->tm_hour = 0;
// both of these will now print the same time! (0:05:14)
// what's linking them??
// print the scheduled time
printf ("Current Time : %2d:%02d:%02d\n", uiuctime->tm_hour, uiuctime->tm_min, uiuctime->tm_sec);
printf ("Scheduled Time : %2d:%02d:%02d\n", dispatchtime->tm_hour, dispatchtime->tm_min, dispatchtime->tm_sec);
}
struct tm* Tracker::uiuctime_tm(){
time_t uiucTime;
struct tm *ts_uiuc;
// give currentTime the current time
time(&uiucTime);
// change the time zone to UIUC
putenv("TZ=CST6CDT");
tzset();
// get the localtime for the tz selected
ts_uiuc = localtime(&uiucTime);
// set back the current timezone
unsetenv("TZ");
tzset();
// set back our results
return ts_uiuc;
}
struct tm* Tracker::dispatchtime_tm(){
time_t currentTime;
struct tm *ts_dispatch;
// give currentTime the current time
time(¤tTime);
// get the localtime for the tz selected
ts_dispatch = localtime(¤tTime);
// set back our results
return ts_dispatch;
}
