[SOLVED] clock()?

nushki · 05-11-2011, 12:14 PM

Hi all,

im trying to calculate how much time does my program run, use very simple script

clock_t end, start;
start= clock();
int i;
printf("initial %d\n",(int)start);

for(i=0;i<20;i++)
{
end=clock();
printf("Time elapsed: %d\n",(int)end);
}

but it outputs 0 all the time. cant figure out where could be the problem.

any ideas?

JohnGraham · 05-11-2011, 02:10 PM

Quote:

Originally Posted by nushki

...it outputs 0 all the time.

That's because your process is using basically no processor time, since it's not doing anything. Try doing something like this (without enabling any optimization):

Code:

#include <stdio.h>
#include <time.h>

int main(void)
{
    clock_t end, start;
    start = clock();
    int i;
    printf("initial %d\n", (int) start);

    for (i = 0; i < 20; i++) {
        end = clock();
        printf("Time elapsed: %d\n", (int) end);
        int p, q, r;
        for (p = 0 ; p < 1000 ; p++)
            for (q = 0 ; q < 1000 ; q++)
                for (r = 0 ; r < 1000 ; r++)
                    printf("");
    }
}

nushki · 05-11-2011, 02:50 PM

oh my gush, you are right!!! thank you so much!!!!