runtime log

[Huibuh]

I want to check the runtime of a part of my program. I chose

#include <time.h>

int runtime

time_t start, end;

start=time(NULL);

end=time(NULL);

runtime=difftime (end, start);

The result was zero, so obviously it is not exact enough. I found the
function CLOCK icw CLOCKS_PER_SEC but I have no idea how to use.

Any idea?

Thanks in advance Dieter

[Victor Bazarov]

Huibuh wrote:

[...] I found the
function CLOCK icw CLOCKS_PER_SEC but I have no idea how to use.

Any idea?

How about you read a reference or something? Go Google for it
and you will find plenty of information. Why involve other human
beings into what you can do alone?

[Robbie Hatley]

"Huibuh" wrote:

time_t start, end;
start=time(NULL);
end=time(NULL);
runtime=difftime (end, start);

The result was zero

The time elapsed between two executive commands on most modern
computers is something around a nanosecond. Yes, that's pretty
damn close to zero. And since it's certainly much less than
than one tick of your timer, yes, you will get zero.

Try something like this:

double trouble = 0.000386;
start=time(NULL);
for (long int i = 0; i<1000000000; ++i)
{
trouble *= 1.000238; // waste some time
}
end=time(NULL);

I think you'll find the elapsed time is no longer zero.

--
Cheers,
Robbie Hatley
Tustin, CA, USA
email: lonewolfintj at pacbell dot net
web: home dot pacbell dot net slant earnur slant