I would like to think that some of the software I'm writing today will be used in 30 years. But I am also aware that a lot of it is based upon the UNIX tradition of exposing time as the number of seconds since 1970.
#include <stdio.h>
#include <time.h>
#include <limits.h>
void print(time_t rt) {
struct tm * t = gmtime(&rt);
puts(asctime(t));
}
int main() {
print(0);
print(time(0));
print(LONG_MAX);
print(LONG_MAX+1);
}
Execution results in:
- Thu Jan 1 00:00:00 1970
- Sat Aug 30 18:37:08 2008
- Tue Jan 19 03:14:07 2038
- Fri Dec 13 20:45:52 1901
The functions ctime(), gmtime(), and localtime() all take as an argument a time value representing the time in seconds since the Epoch (00:00:00 UTC, January 1, 1970; see time(3) ).
I wonder if there is anything proactive to do in this area as a programmer, or are we to trust that all software systems (aka Operating Systems) will some how be magically upgraded in the future?
Update It would seem that indeed 64-bit systems are safe from this:
import java.util.*;
class TimeTest {
public static void main(String[] args) {
print(0);
print(System.currentTimeMillis());
print(Long.MAX_VALUE);
print(Long.MAX_VALUE + 1);
}
static void print(long l) {
System.out.println(new Date(l));
}
}
- Wed Dec 31 16:00:00 PST 1969
- Sat Aug 30 12:02:40 PDT 2008
- Sat Aug 16 23:12:55 PST 292278994
- Sun Dec 02 08:47:04 PST 292269055
But what about the year 292278994?
