[lnkForumImage]
TotalShareware - Download Free Software
Confronta i prezzi di migliaia di prodotti.
Asp Forum
 Home | Login | Register | Search 


 

Forums >

comp.lang.c++

Acessing the "time" Part of time_t Value

mrc2323

11/20/2008 7:04:00 AM

How do I mask out all but the _time_ components of a time_t value?
Specifically, I have the following:
time_t wTime = 1226764757;
I happen to know that this is November 16, 2008 @ 8:59:17, but I have
many other such items from which I want to use only the _time_ portion
(e.g. 8:59:17). How do I eliminate the "date" portions of either the
time_t value or the number I assign to it? TIA
4 Answers

miso.liptak

11/20/2008 7:56:00 AM

0

On Nov 20, 8:03 am, mrc2...@cox.net (Mike Copeland) wrote:
>    How do I mask out all but the _time_ components of a time_t value?  
> Specifically, I have the following:
>         time_t wTime = 1226764757;
>    I happen to know that this is November 16, 2008 @ 8:59:17, but I have
> many other such items from which I want to use only the _time_ portion
> (e.g. 8:59:17).  How do I eliminate the "date" portions of either the
> time_t value or the number I assign to it?  TIA

Is number of seconds since midnight what you want? time(0) % 86400?
m.

Pete Becker

11/20/2008 12:04:00 PM

0

On 2008-11-20 02:03:33 -0500, mrc2323@cox.net (Mike Copeland) said:

> How do I mask out all but the _time_ components of a time_t value?
> Specifically, I have the following:
> time_t wTime = 1226764757;
> I happen to know that this is November 16, 2008 @ 8:59:17, but I have
> many other such items from which I want to use only the _time_ portion
> (e.g. 8:59:17). How do I eliminate the "date" portions of either the
> time_t value or the number I assign to it? TIA

Use gmtime() or localtime() to convert it to a tm.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

Pete Becker

11/20/2008 12:08:00 PM

0

On 2008-11-20 02:56:08 -0500, "miso.liptak" <miso.liptak@gmail.com> said:

> On Nov 20, 8:03 am, mrc2...@cox.net (Mike Copeland) wrote:
>>    How do I mask out all but the _time_ components of a time_t value?
>  
>> Specifically, I have the following:
>>         time_t wTime = 1226764757;
>>    I happen to know that this is November 16, 2008 @ 8:59:17, but I h
> ave
>> many other such items from which I want to use only the _time_ portion
>> (e.g. 8:59:17).  How do I eliminate the "date" portions of either the
>> time_t value or the number I assign to it?  TIA
>
> Is number of seconds since midnight what you want? time(0) % 86400?
> m.

The requirement (from the C standard) is that time_t is an "arithmetic
type capable of representing times ...". That's all. It doesn't have to
represent seconds, nor does it have to be based on midnight.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

James Kanze

11/20/2008 1:44:00 PM

0

On Nov 20, 8:56 am, "miso.liptak" <miso.lip...@gmail.com> wrote:
> On Nov 20, 8:03 am, mrc2...@cox.net (Mike Copeland) wrote:

> > How do I mask out all but the _time_ components of a time_t
> > value? Specifically, I have the following:
> > time_t wTime = 1226764757;
> > I happen to know that this is November 16, 2008 @ 8:59:17,
> > but I have many other such items from which I want to use
> > only the _time_ portion (e.g. 8:59:17). How do I eliminate
> > the "date" portions of either the time_t value or the number
> > I assign to it? TIA

> Is number of seconds since midnight what you want? time(0) %
> 86400?

That depends on how precise and how portable you have to be.
Not all days have exactly 86400 seconds, and time_t can be any
numeric type, with any representation---if it uses the
representation that was current in MS-DOS, your results are
meaningless, and if it is a double, your solution won't even
compile. (But for a lot of uses, it's adequate. It's what I
currently do---but in my case, even if I'm a minute or so off,
it's no big deal, and I only have to support
Unix-likes---Solaris and Linux.)

--
James Kanze (GABI Software) email:james.kanze@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientierter Datenverarbeitung
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34