C++ 64bit timestamp to 32bit time_t

Question

I want to convert a 64bit timestamp (in us) to a date string in order to set system date via system command "date". I found/implemented this solution:

char loc_ach_buf[25];
uint64_t loc_ui64_TimeStamp_us;
time_t loc_t_TimeStamp_s;
...         
loc_t_TimeStamp_s = loc_ui64_TimeStamp_us / 1000000;
strftime(loc_ach_buf, sizeof(loc_ach_buf), "date %Y%m%d%H%M.%S", gmtime(&loc_t_TimeStamp_s));
system(loc_ach_buf);

This works fine, but my problem is, that time_t is a 32bit value on my system and so there will be problems Year 2038 problem . Any ideas how to solve this? Or are there alternatives to strftime.

Answer 1

Why use the system command 'date'? Use the SetSystemTime API call.

Answer 2

I'm not sure which toolset you're working with but the Microsoft compiler supports a function _localtime64_s which will convert a 64-bit time value to the tm structure that you can then use with strftime .

If your CRT doesn't support 64-bit time functions have a look at this: A version of gmtime() that works around the 2038 bug