Re: [Boost-users] convert separate year, month, day, hour, minute, secs, ms to milliseconds since epoch

Subject: Re: [Boost-users] convert separate year, month, day, hour, minute, secs, ms to milliseconds since epoch
From: Leon Mlakar (leon_at_[hidden])
Date: 2019-03-05 08:38:53

On 05.03.2019 07:11, degski via Boost-users wrote:
> On Tue, 5 Mar 2019 at 01:51, Leon Mlakar via Boost-users 
> <boost-users_at_[hidden] <mailto:boost-users_at_[hidden]>> wrote:
>
>     I wonder how this works on Windows with VS2019?
>
>
> It returns 1551766256847 (so the same as 
> https://www.epochconverter.com/, i.e. "Unix Time"), there's no reason 
> to assume it returns something else with VS2019 (AFAICS), until/unless 
> it supports C++20 and the std explicitly changes the behavior  (forces 
> MS to break backward compatibility), you can be assured that it will 
> be doing that for a while (until the Y38 problem raises its head).
>
Thank you for the information.

Behid the question was my, obviously incorrect, assumption that older 
visual studio versions, from times when c++20 was not yet conceived and 
epoch thus not set to Jan 1 AD 1970, are using some different epoch - as 
Microsoft frequently did, like Jan 1 AD 1 (.NET),  Jan 1 AD 1601 (NTFS), 
Jan 1 AD 1980 (DOS, FAT family of file systems). So seeing Microsoft 
embracing a standard thing like posix epoch without screaming and 
kicking is a nice surprise.

And it was late.

Cheers,

Leon

P.S. As for the Y38, std::chrono should be okay as it's not bound to 
32-bit integrals.