How to calculate the number of seconds since January 1st, 1970 ?

How to calculate the number of seconds since January 1st, 1970 ?

[P. Renaud]

Hi all,

I have to calculate the number of seconds since January 1st, 1970
00:00.

I tried using the Calendar package but it always fails with the
Time_Error exception (the minus operator used to calculate the
difference between the current date/time and the reference date/time
is greater than the duration type limit).

How can I do to obtain the correct result ?

Thanks for your help.

P. Renaud

Re: How to calculate the number of seconds since January 1st, 1970 ?

[Joachim Schröer]

P. Renaud wrote:

> Hi all,
> 
> I have to calculate the number of seconds since January 1st, 1970
> 00:00.
> 
> I tried using the Calendar package but it always fails with the
> Time_Error exception (the minus operator used to calculate the
> difference between the current date/time and the reference date/time
> is greater than the duration type limit).
> 
> How can I do to obtain the correct result ?
> 
> Thanks for your help.
> 
> P. Renaud
> 

Hi,

you could download

www.adapower.com\schroer\lib-src.zip

Use one of the "-" functions in package utilities.calendar_utilities.
The functions may be used to calculate what you are looking for.
The package is a version of Grady Booch's calendar_utilities with some
additional features.

Best regards
	J. Schr�er

Re: How to calculate the number of seconds since January 1st, 1970 ?

[David C. Hoos]

----- Original Message ----- 
From: "P. Renaud" <patrick.renaud@transport.alstom.com>
Newsgroups: comp.lang.ada
To: <comp.lang.ada@ada.eu.org>
Sent: Tuesday, April 02, 2002 3:24 AM
Subject: How to calculate the number of seconds since January 1st, 1970 ?


> Hi all,
> 
> I have to calculate the number of seconds since January 1st, 1970
> 00:00.
> 
> I tried using the Calendar package but it always fails with the
> Time_Error exception (the minus operator used to calculate the
> difference between the current date/time and the reference date/time
> is greater than the duration type limit).
> 
> How can I do to obtain the correct result ?
> 
What's wrong with this?

with Ada.Calendar;
with Ada.Text_IO;
procedure Seconds is
   Elapsed_Time : Duration;
   Unix_Epoch : constant Ada.Calendar.Time :=
     Ada.Calendar.Time_Of
     (Year    => 1970,
      Month   => 1,
      Day     => 1,
      Seconds => 0.0);
   use type Ada.Calendar.Time;
begin
   Elapsed_Time := Ada.Calendar.Clock - Unix_Epoch;
   Ada.Text_IO.Put_Line (Duration'Image (Elapsed_Time));
end Seconds;

What compiler are you using, for which the resulting Duration
value is out of range?

David Hoos

> Thanks for your help.
> 
> P. Renaud
> _______________________________________________
> comp.lang.ada mailing list
> comp.lang.ada@ada.eu.org
> http://ada.eu.org/mailman/listinfo/comp.lang.ada
> 

RE: How to calculate the number of seconds since January 1st, 1970 ?

[Mário Amado Alves]

> . . .
> What compiler are you using, for which the resulting Duration value is
out of range?

Indeed, GNAT's Duration spans circa 6 centuries:

   type Duration is delta 0.000000001
     range -((2 ** 63 - 1) * 0.000000001) ..
           +((2 ** 63 - 1) * 0.000000001);
   for Duration'Small use 0.000000001;

So the original poster must be using either

  - another compiler
  - bad data
  - good data from the Howard Foundation ;-)

Cheers,
--MAA

RE: How to calculate the number of seconds since January 1st, 1970 ?

[tmoran]

>Indeed, GNAT's Duration spans circa 6 centuries:
  But the ARM only requires Duration to include -86400.0 .. 86400.0

>So the original poster must be using either
>
>  - another compiler
  So he can either lock himself into ACT as a vendor, or use one of the
previously mentioned utilities (e.g. see www.adapower.com).
  Of course Ada.Calendar.Clock returns a rather arbitrary number dependent
on the time zone and the accuracy of the system operator's watch and
the accuracy of the computer's clock, so it's a rather nominal source
for the actual number of seconds since 1/1/70 00:00:00