Using clock() to measure time in C

Question

I've written this code and it does not return the proper time (probably some piece of the code is wrong). And is there any other way to measure time between two actions more precisely then this (in c)?

float measureTime(clock_t start, clock_t end){

    float totalSeconds;    

    totalSeconds = ((long double)(end - start))/CLOCKS_PER_SEC;

    printf("%.6f", totalSeconds);

    return(totalSeconds);
}

int main(){

    clock_t start, end;

    start = clock();
    //piece of code here
    //
    end = clock();

    measureTime(start, end);

    return (EXIT_SUCCESS);
}

...except MSVC's `clock()` is non-standard, it measures wall time. — Weather Vane, Nov 26 '16 at 18:45
There are *a lot* of questions about measuring execution time, here is [one with several links](http://stackoverflow.com/questions/16740014/computing-time-in-linux-granularity-and-precision), and here is [another with large voting](http://stackoverflow.com/questions/5248915/execution-time-of-c-program). — Weather Vane, Nov 26 '16 at 19:25
The cast to `long double` and then assignment to `float` is incongruous — not technically wrong, but not very plausible. I'm from old school C; just use `double` unless there's a storage reason to use `float`. — Jonathan Leffler, Nov 26 '16 at 21:44

score 0 · Accepted Answer · edited May 23 '17 at 11:59

0

As Weather Vane said, there are many questions about time measuring in c. Here is one How do I measure time in C?.

Just a comment on your method, you will probably get 0.0s as result if your piece code contains few lines of execution (if you use a modern computer with 4 cpus with a higher frequency, the piece of code will be executed on a few clock cycles).

edited May 23 '17 at 11:59

Community

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answered Nov 26 '16 at 20:47

shamba

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Using clock() to measure time in C

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