How to get current time as long or ulong?

[Charles Hixson via Digitalmars-d-learn]

On 07/06/2016 10:32 AM, H. S. Teoh via Digitalmars-d-learn wrote:
> On Wed, Jul 06, 2016 at 10:19:19AM -0700, Charles Hixson via Digitalmars-d-learn wrote:
> [...]
>> The same time needs to be used for two different purposes (or I have
>> to keep two separate times).  One time is used during a particular run
>> of the program to compare when two different things happened. This
>> needs fine discrimination...millisecond level.  The other needs to be
>> used to order events happening over a period of time.  This needs to
>> be at the hour level, and the minute level is better.  But it needs to
>> work over years.  That's why I originally said UnixTime...and UnixTime
>> would work fine, but problems might happen if it were in use in
>> 2029(?*).  Since D supports a 64 bit time, not using it would seem to
>> be unreasonable.  I looked into scaling it, but either I use more than
>> 32 bits, or I need to keep two times.  So the long version of SysTime
>> seems to be what I want.  That will even let me compare things against
>> books published in the Classical Greek period, and doesn't threaten to
>> roll over.  It's more precise than I need, but there's no one time of
>> lesser precision that will do everything I want.
> The problem with this is that the system clock may change.  Would your
> program continue to function correctly if, during execution, the user
> changes the system clock? Or if the OS in the background syncs with a
> remote NTP server and loses/gains a few seconds/minutes during which
> events are happening that record timestamps? I.e., some events might
> have their timestamps out-of-order with the actual sequence of events if
> you use system time.
>
>
> T
It would err in a trivial way, which might require reloading something 
from disk.  So an occasional mistake of that nature isn't a problem.