Re: time_t problem

From:
"Doug Harrison [MVP]" <dsh@mvps.org>
Newsgroups:
microsoft.public.vc.mfc
Date:
Wed, 07 Jun 2006 10:47:32 -0500
Message-ID:
<ntsd82t7t4qqpbi0sn9t8hbjrf60rcaist@4ax.com>
On Wed, 7 Jun 2006 18:33:48 +0800, "Tan" <tan@tiss-msc.com> wrote:

Hi,

I having a problem to convert time_t to DateTime in .Net.

Eg.

In C++, I used the following method:

time_t a 1149719862L;
CTime timeTemp = a;
timeTemp.Format(_T("%Y-%m-%d %I:%M:%S %p"))

Result:
2006-06-07 03:37:42 PM

In .Net,

long time_t = 1149719862L;
long win32FileTime = 10000000*time_t + 116444736000000000;
DateTime dt = DateTime.FromFileTime(win32FileTime);
String.Format("{0:dd/MM/yyyy hh:mm:ss tt}", dt);

Result:
08/06/2006 06:37:42 AM

May I know why the above convertion is wrong? Please guide me on how to
convert time_t to DateTime.
Thank you in advance.


Looks like a time zone difference. You always need to check the docs to
determine whether or not the functions you're using take or return local
time or UTC. Some other comments:

1. time_t is a type, so don't use it as a variable name.

2. It's more portable and reliable to get a time_t from a function that
takes a broken-down time, like mktime.

3. You can convert a SYSTEMTIME to FILETIME with SystemTimeToFileTime,
which would allow you to bypass time_t and the Standard C time functions.

--
Doug Harrison
Visual C++ MVP

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