Re: +3.0 microsecond for iterating empty vectors

From:
=?ISO-8859-1?Q?Erik_Wikstr=F6m?= <Erik-wikstrom@telia.com>
Newsgroups:
comp.lang.c++
Date:
Fri, 26 May 2006 08:58:44 GMT
Message-ID:
<8rzdg.2034$E02.475@newsb.telia.net>
On 2006-05-26 02:55, krbyxtrm wrote:

Ayon kay krbyxtrm:

hello people,
i have implemented my code this way

start = read_timer(); // for profiling
    if ( !any_vec.empty() )
    {

    std::for_each(
        any_vec.begin(),
        any_vec.end(),
        retrieve); // where retrieve is an empty function for now...

    }
end = read_timer();
duration = end - start ; // minus counter error

with this code and having empty callback function,
it duration = 1.2e-1 us

BTW, IS FOR VECTOR WITH 1 ELEMENT


It might be of interest to try with more elements, the increase in time
is not necessarily linear with the number of elements. Caches for
example can be a part of it, if you get a cache-miss on the first
element that will take some time, but the next element will be much
faster. To get good measures you should use more elements and run the
test many times and calculate the average.

Erik WikstrFm
--
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