64-bit Unix timestamp conversion

c++ linux 64-bit 32bit-64bit time-t
Adam Trhon picture Adam Trhon · Oct 27, 2011 · Viewed 16.7k times · Source

Is there any C++ implementation of 64-bit Unix timestamp conversions for 32-bit systems? I need to convert struct tm to 64-bit integer and vice versa, including leap years, time zones, UTC. Also need it portable, at least for GNU/Linux and Windows.

Answer

Alexei Khlebnikov picture Alexei Khlebnikov · Nov 7, 2011

You need:

typedef long long time64_t; 
time64_t mktime64(struct tm *t); 
struct tm* localtime64_r(const time64_t* t, struct tm* p);

Originally (in 2011) this answer contained links to 2038bug.com where it was possible to download the small pivotal_gmtime_r library, containing the mentioned functions. The library has been removed from 2038bug.com back then, the links became broken and were removed from the answer by a moderator. Seems like that pivotal_gmtime_r code can now be found here:

https://github.com/franklin373/mortage/tree/master/time_pivotal

Also, I've found another, more recent library, called y2038, that also implements mktime64 and localtime64_r:

https://github.com/evalEmpire/y2038

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