Getting time in milliseconds

[Pravesh]

Hi:
is there a way to get current system time in milliseconds...
which functions and headers??

thanks
pravesh

[Mike Wahler]

"Pravesh" <pr************ ****@yahoo.com> wrote in message
news:e5******** *************** ***@posting.goo gle.com...

Hi:
is there a way to get current system time in milliseconds...
Not portably.
which functions and headers??

The standard functions for retrieving system time and
working with time are declared by the header <time.h>.
They including 'time()', 'localtime()', and 'gmtime()',
among others. However, the resolution of the time
is implementation-specific.

-Mike

[Merrill & Michele]

> > Pravesh:

is there a way to get current system time in milliseconds...

"Mike Wahler" wrote:
Not portably. which functions and headers??

The standard functions for retrieving system time and
working with time are declared by the header <time.h>.
They including 'time()', 'localtime()', and 'gmtime()',
among others. However, the resolution of the time
is implementation-specific.

But if, conjecturally, some one put a gun to your head and said "I need
milliseconds from the arbitrary machine using C compiled on said machine,"
you wouldn't get your brains blown out, correct? In particular, is this not
true if you let a program "warm up" to an OS for, say, a minute? MPJ

[Mike Wahler]

"Merrill & Michele" <be********@com cast.net> wrote in message
news:er******** ************@co mcast.com...

Pravesh:
is there a way to get current system time in milliseconds...

"Mike Wahler" wrote:
Not portably. which functions and headers??

The standard functions for retrieving system time and
working with time are declared by the header <time.h>.
They including 'time()', 'localtime()', and 'gmtime()',
among others. However, the resolution of the time
is implementation-specific.

But if, conjecturally, some one put a gun to your head and said "I need
milliseconds from the arbitrary machine using C compiled on said machine,"
you wouldn't get your brains blown out, correct?

It's entirely possible that I would. "Arbitrary machine" might not
have the requested functionality. Or perhaps a C translator for it
does not exist.
In particular, is this not
true if you let a program "warm up" to an OS for, say, a minute? MPJ

Some platforms, operating systems, and C implementations do provide
the requested functionality, others do not. Also note that a C program
need not be hosted by an operating system at all.

-Mike

[Jack Klein]

On Mon, 8 Nov 2004 19:34:34 -0600, "Merrill & Michele"
<be********@com cast.net> wrote in comp.lang.c:

Pravesh:
is there a way to get current system time in milliseconds...

"Mike Wahler" wrote:
Not portably.

which functions and headers??

The standard functions for retrieving system time and
working with time are declared by the header <time.h>.
They including 'time()', 'localtime()', and 'gmtime()',
among others. However, the resolution of the time
is implementation-specific.

But if, conjecturally, some one put a gun to your head and said "I need
milliseconds from the arbitrary machine using C compiled on said machine,"
you wouldn't get your brains blown out, correct? In particular, is this not
true if you let a program "warm up" to an OS for, say, a minute? MPJ

Sure, you can always multiply the return value of difftime() by 1000.

But there are a lot of systems out there that don't track time
accurately to the millisecond.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
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alt.comp.lang.l earn.c-c++
http://www.contrib.andrew.cmu.edu/~a...FAQ-acllc.html

[Merrill & Michele]

> Pravesh:
> is there a way to get current system time in milliseconds...

"Mike Wahler" wrote:
Not portably.

> which functions and headers??

The standard functions for retrieving system time and
working with time are declared by the header <time.h>.
They including 'time()', 'localtime()', and 'gmtime()',
among others. However, the resolution of the time
is implementation-specific.

But if, conjecturally, some one put a gun to your head and said "I need
milliseconds from the arbitrary machine using C compiled on said machine," you wouldn't get your brains blown out, correct? In particular, is this not true if you let a program "warm up" to an OS for, say, a minute?

Jack Klein:
Sure, you can always multiply the return value of difftime() by 1000.

But there are a lot of systems out there that don't track time
accurately to the millisecond.

That systems don't track milliseconds doesn't mean that we can't track THEM
to the millisecond. That is, with a little elbow grease and the view that
the occurence of the next second can be seen as a Poisson process. The
following code is crude, but I think it illustrates that one isn't shackled
by notions smaller than a second. I think I recall that a "jiffy" is 10^-52
seconds. MPJ

#include <stdio.h>
#include <time.h>
int main (){
time_t timer;
long i, counter, aboutbillion, fiveseconds;
aboutbillion = 0;
counter = 0;
fiveseconds = (long)(time(&ti mer) + 5);
while (aboutbillion < fiveseconds){
aboutbillion = (long)time(&tim er);
++counter;
}
printf (" counter= %ld\n", counter);
printf (" timer= %ld\n", aboutbillion);
printf (" and five= %ld\n", fiveseconds);
return 0;
}

[suman kar]

pr************* ***@yahoo.com (Pravesh) wrote in message news:<e5******* *************** ****@posting.go ogle.com>...

Hi:
is there a way to get current system time in milliseconds...
which functions and headers??

Short reply:in C, no.

Long reply:But there are libraries that define certain structures and functions
that let you manipulate time values.That is system/implementation dependant.Also
you will need to know why and where you are using it.And that's exactly OT here.
E.g:if you are on *nix systems you can probably find something like time.h,
look up on it.And Google for it!There are lots of resources available.

HTH
Suman.

[Christian Kandeler]

Jack Klein wrote:

Sure, you can always multiply the return value of difftime() by 1000.

And then divide the result by 1000000.
Christian

[ranjeet]

pr************* ***@yahoo.com (Pravesh) wrote in message news:<e5******* *************** ****@posting.go ogle.com>...

Hi:
is there a way to get current system time in milliseconds...
which functions and headers??
Yes, there is Fucntion to compute/get time of the specified fuction.
(How much fucntion is taking time to execute),I think this is your Goal.

for linux --> #include <sys/time.h>
gettimeofday

for windows --> #include <time.h>
GetTickCount is the function
See the both the arguments in it
and You will be able to get the Time in milliseconds
Hope this will help you out.
If You have the problem then drop the mail.

Enjoy
Ranjeet
thanks
pravesh

[Jens.Toerring]

Merrill & Michele <be********@com cast.net> wrote:

Jack Klein:
Sure, you can always multiply the return value of difftime() by 1000.

But there are a lot of systems out there that don't track time
accurately to the millisecond.

That systems don't track milliseconds doesn't mean that we can't track THEM
to the millisecond. That is, with a little elbow grease and the view that
the occurence of the next second can be seen as a Poisson process. The
following code is crude, but I think it illustrates that one isn't shackled
by notions smaller than a second. I think I recall that a "jiffy" is 10^-52
seconds. MPJ #include <stdio.h>
#include <time.h>
int main (){
time_t timer;
long i, counter, aboutbillion, fiveseconds;
aboutbillion = 0;
counter = 0;
fiveseconds = (long)(time(&ti mer) + 5);
There's nothing that guarantees that time_t is a time in seconds on
all systems, at least the C standard does only says that time_t is
a "arithmetic type capable of representing times".
while (aboutbillion < fiveseconds){
aboutbillion = (long)time(&tim er);
++counter;
}
printf (" counter= %ld\n", counter);
printf (" timer= %ld\n", aboutbillion);
printf (" and five= %ld\n", fiveseconds);
return 0;
}

Even if time_t does return times in seconds that won't do you any
good on a multi-tasking OS. What you try to do here is measure the
time a call of time() takes - but that will only give you a useful
result if the process gets all the CPU time during that 5 seconds.
But on most modern operating systems the CPU time gets distributed
between different processes, and the OS itself uses some time for
it's own purposes. So you don't have a chance to get a reproducible
value that way since you don't have any idea how much time the other
processes get (you don't even know how many there are) and how much
time the OS is going to need.
Regards, Jens
--
\ Jens Thoms Toerring ___ Je***********@p hysik.fu-berlin.de
\______________ ____________ http://www.toerring.de