time in milliseconds 
Author Message
 time in milliseconds

Hi!

How can I get a time in milliseconds, e.g. if
Im searching in a file and later I want to say:
"The objekt youre looking for has been found within
237 milliseconds"?

Thanx and greetings
Stephan



Tue, 21 Oct 2003 14:23:21 GMT  
 time in milliseconds


Quote:
> Hi!

> How can I get a time in milliseconds, e.g. if Im searching in
> a file and later I want to say: "The objekt youre looking for
> has been found within 237 milliseconds"?

The clock() function may be used for such things but your
system/compiler may have some extra function handy that may
have a better resollution.

To get the time elapsed between to calls to clock() in seconds
devide the difference with CLOCKS_PER_SEC.

--

"LISP  is worth learning for  the profound enlightenment  experience
you will have when you finally get it; that experience will make you
a better programmer for the rest of your days."   -- Eric S. Raymond



Tue, 21 Oct 2003 14:40:17 GMT  
 time in milliseconds


Quote:


>> Hi!

>> How can I get a time in milliseconds, e.g. if Im searching in
>> a file and later I want to say: "The objekt youre looking for
>> has been found within 237 milliseconds"?

>The clock() function may be used for such things but your

The clock() function measures CPU time used and not elapsed time so
it may or may not be what is needed. For I/O operations probably not.
It also has no guarantees concerning resolution, although it is
sub-second on most implementations.

Quote:
>system/compiler may have some extra function handy that may
>have a better resollution.

That is usually the best approach if you really need this sort of
precision.

--
-----------------------------------------


-----------------------------------------



Tue, 21 Oct 2003 22:01:14 GMT  
 time in milliseconds
Try ftime().

Feng

Quote:





> >> Hi!

> >> How can I get a time in milliseconds, e.g. if Im searching in
> >> a file and later I want to say: "The objekt youre looking for
> >> has been found within 237 milliseconds"?

> >The clock() function may be used for such things but your

> The clock() function measures CPU time used and not elapsed time so
> it may or may not be what is needed. For I/O operations probably not.
> It also has no guarantees concerning resolution, although it is
> sub-second on most implementations.

> >system/compiler may have some extra function handy that may
> >have a better resollution.

> That is usually the best approach if you really need this sort of
> precision.

> --
> -----------------------------------------


> -----------------------------------------

Feng He
Swarthmore '03


Tue, 21 Oct 2003 22:39:12 GMT  
 time in milliseconds

hi,
     If milli second precision is all what you need then you
     can look up the bios data area at 40:6ch
     both before and after your code and use the difference
     as a measure of the time taken.

     Alternately Turbo C++ offers a function clock() <time.h>
     which can be used as well.

     The problem here is that you can reach a precision
     of only 1/18.2 of a second as both rely on the System's RTC
     which counts 18.2 times a second.
     [ should be fairly enough for your file processing code.].

     In assembly you can achieve micro-second accuracy by using the
     rdtsc (ReaD Time Stamp Counter) instruction provided by
     the pentium class of processors.

     Anything else ?

     Cheers.



Tue, 21 Oct 2003 23:25:02 GMT  
 time in milliseconds

Quote:

> hi,
>      If milli second precision is all what you need then you
>      can look up the bios data area at 40:6ch
>      both before and after your code and use the difference
>      as a measure of the time taken.

>      Alternately Turbo C++ offers a function clock() <time.h>
>      which can be used as well.

>      The problem here is that you can reach a precision
>      of only 1/18.2 of a second as both rely on the System's RTC
>      which counts 18.2 times a second.
>      [ should be fairly enough for your file processing code.].

>      In assembly you can achieve micro-second accuracy by using the
>      rdtsc (ReaD Time Stamp Counter) instruction provided by
>      the pentium class of processors.

>      Anything else ?

Yes: Don't post HTML to usenet. stay on topic. c.l.c. is
for discussing programing in the c language. This guaranties
portability of the code. Your suggestions are accurate for
a given architecture only.
Tobias.


Wed, 22 Oct 2003 00:04:35 GMT  
 time in milliseconds

Quote:

>    Part 1.1    Type: Plain Text (text/plain)
>            Encoding: quoted-printable

illegible.  Don't use html, mime, or attachments in newsgroups.

--

http://www.qwikpages.com/backstreets/cbfalconer :=(down for now)
   (Remove "NOSPAM." from reply address. my-deja works unmodified)



Wed, 22 Oct 2003 02:27:08 GMT  
 time in milliseconds

Quote:
>Try ftime().

How do you know there is such a thing on the OP's system?  Or did they
add this function to the standard while I wasn't looking?

Get a clue!

Dan
--
Dan Pop
CERN, IT Division

Mail:  CERN - IT, Bat. 31 1-014, CH-1211 Geneve 23, Switzerland



Wed, 22 Oct 2003 13:05:57 GMT  
 time in milliseconds

Quote:

>hi,
>     If milli second precision is all what you need then you
>     can look up the bios data area at 40:6ch

How do I do that on my Digital Unix workstation?

Quote:
>     both before and after your code and use the difference
>     as a measure of the time taken.

>     Alternately Turbo C++ offers a function clock() <time.h>
>     which can be used as well.

Too bad it doesn't measure *real* time.

Quote:
>     The problem here is that you can reach a precision
>     of only 1/18.2 of a second as both rely on the System's RTC
>     which counts 18.2 times a second.=20

I was under the misguided impression that my workstation's clock()
implementation relies on the system's time slice, which happens to be
1/60 of a second.  Oh well, one learns something new every day!

Quote:
>     [ should be fairly enough for your file processing code.].

>     In assembly you can achieve micro-second accuracy by using the
>     rdtsc (ReaD Time Stamp Counter) instruction provided by
>     the pentium class of processors.

How do you know the OP's system has a Pentium class processor?  Mine
certainly hasn't!

Quote:
>     Anything else ?

Yup: this is comp.lang.c, a platform neutral newsgroup and the OP didn't
make any mention about what kind of system(s) he's using or how portable
the solution should be.  So, your reply is pure bullshit, both in
presentation and in contents.

Dan
--
Dan Pop
CERN, IT Division

Mail:  CERN - IT, Bat. 31 1-014, CH-1211 Geneve 23, Switzerland



Wed, 22 Oct 2003 13:14:00 GMT  
 time in milliseconds

Quote:



> > Hi!

> > How can I get a time in milliseconds, e.g. if Im searching in
> > a file and later I want to say: "The objekt youre looking for
> > has been found within 237 milliseconds"?

> The clock() function may be used for such things but your

Since clock() returns processor time used by current program, I assume this
is not what OP want.

Quote:
> system/compiler may have some extra function handy that may
> have a better resollution.

> To get the time elapsed between to calls to clock() in seconds
> devide the difference with CLOCKS_PER_SEC.

Well, time() is the standard function C provide for this. For higher
resolution than seconds, OP need to use a system dependent function.

--
Tor <torust AT online DOT no>



Wed, 22 Oct 2003 18:57:15 GMT  
 time in milliseconds

Quote:
>Well, time() is the standard function C provide for this. For higher
>resolution than seconds, OP need to use a system dependent function.

                             ^^^^
The OP *may* need to use a system dependent function.  There is nothing
preventing time() from providing microsecond resolution.

Dan
--
Dan Pop
CERN, IT Division

Mail:  CERN - IT, Bat. 31 1-014, CH-1211 Geneve 23, Switzerland



Thu, 23 Oct 2003 06:08:54 GMT  
 time in milliseconds

Quote:



>>Well, time() is the standard function C provide for this. For higher
>>resolution than seconds, OP need to use a system dependent function.
>                             ^^^^
>The OP *may* need to use a system dependent function.  There is nothing
>preventing time() from providing microsecond resolution.

Although either way it has to make use of a system dependent feature.

--
-----------------------------------------


-----------------------------------------



Fri, 24 Oct 2003 03:36:35 GMT  
 time in milliseconds

Quote:



> >Well, time() is the standard function C provide for this. For higher
> >resolution than seconds, OP need to use a system dependent function.
>                              ^^^^
> The OP *may* need to use a system dependent function.  There is nothing
> preventing time() from providing microsecond resolution.

Even so, that will not help OP much, unless you know a way to extract such
information in a standard way.

--
Tor <torust AT online DOT no>



Fri, 24 Oct 2003 03:38:40 GMT  
 time in milliseconds

Quote:



>> >Well, time() is the standard function C provide for this. For higher
>> >resolution than seconds, OP need to use a system dependent function.
>>                              ^^^^
>> The OP *may* need to use a system dependent function.  There is nothing
>> preventing time() from providing microsecond resolution.

>Even so, that will not help OP much, unless you know a way to extract such
>information in a standard way.

    4.12.2.2 The difftime function

    Synopsis

             #include <time.h>
             double difftime(time_t time1, time_t time0);
             ^^^^^^
    Description

    The difftime function computes the difference between two calendar
    times: time1 - time0 .

    Returns

    The difftime function returns the difference expressed in seconds
    as a double.
    ^^^^^^^^^^^
Is this standard enough for you?

Dan
--
Dan Pop
CERN, IT Division

Mail:  CERN - IT, Bat. 31 1-014, CH-1211 Geneve 23, Switzerland



Fri, 24 Oct 2003 22:48:19 GMT  
 time in milliseconds

Quote:

>     The difftime function returns the difference expressed in seconds

                                                             ^^^^^^^^^^

Quote:
>     as a double.
>     ^^^^^^^^^^^
> Is this standard enough for you?

> Dan

Is that far enough from an answer to the OP for you?

Micah



Sat, 25 Oct 2003 01:06:38 GMT  
 
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