c++ - Converting time_t to int

Question

I want to convert a given time into epoch(time_t) and vice versa. can anyone tell what is the routine or algorithm for this?

Thanks

Update

 epoch_strt.tm_sec = 0;
 epoch_strt.tm_min = 0;
 epoch_strt.tm_hour = 0;
epoch_strt.tm_mday = 1;
epoch_strt.tm_mon = 1;
epoch_strt.tm_year = 70;
 epoch_strt.tm_isdst = -1;

double nsecs = difftime(curtime, basetime);//current time from system, I converrting it to struct tm

but this always return 32399 for some reason.

Answer 1

You should cast it to a long int instead of int.

long int t = static_cast<long int> (time(NULL));

An int might not be enough to hold the time, for example, on my platform, time_t is a typedef of __int64.