measuring function execution time

This is a discussion on measuring function execution time within the C++ Programming forums, part of the General Programming Boards category; hi, how can i do this? i tried using gettickcount of windows.h and also the clock function in time.h but ...

  1. #1
    nik
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    measuring function execution time

    hi, how can i do this?

    i tried using gettickcount of windows.h and also the clock function in time.h but none worked, it gave 0 as a result

    thanks in advance

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    on windows you can try using QueryPerformanceCounter(). a simple example follows:
    Code:
    LARGE_INTEGER frequency;
    LARGE_INTEGER before, after;
    QueryPerformanceFrequency(&frequency);
    QueryPerformanceCounter(&before);
    // call function here
    QueryPerformanceCounter(&after);
    double seconds = double(after - before) / double(frequency);
    Last edited by Elkvis; 03-11-2011 at 03:59 PM. Reason: removed unnecessary variables

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    You can try this one:

    Code:
    int example(void)
    {
    DWORD start_time=GetTickCount(); ///learn the time at start
    
    ///do some stuff here
    
    return GetTickCount()-start_time; //calculate how much time has passed and return it.
    }
    I'm not sure if it is what you want, but I hope it works, i'm having a compiler problem and i couldn't test it.

  4. #4
    nik
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    i tried the gettickcount but for some reason it didnt return anything except 0

    as for QueryPerformanceCounter

    i tried your code, but it didnt work i put for before, after and frequency a .QuadPart and it did work, does anyone know why?

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    could you post the function so that i could help?

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    Quote Originally Posted by nik View Post
    i tried the gettickcount but for some reason it didnt return anything except 0

    as for QueryPerformanceCounter

    i tried your code, but it didnt work i put for before, after and frequency a .QuadPart and it did work, does anyone know why?
    yup, it's because LARGE_INTEGER is actually a union, and not a native type. as such, it has a member called QuadPart which is a 64-bit integer. I forgot about this when I posted the code. sorry about that.

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