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[C++] Masurarea timpului


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In acest tutorial am decis sa masuram performanta executarii a doua bucati de cod diferite. Am ales doua metode diferite de a calcula restul impartirii lui X la Y, fara a folosi operatorul %.

#include <chrono> // pentru calcularea timpului
#include <iostream> // pentru input si output

const int number_of_tests = 1e5; // numarul de teste rulate

int calc_remainder_with_repeated_substractions(int x, int y)
{
    while (x >= 0) {
        x -= y;
    }
    x += y;

    return x;
}

int calc_remainder_with_math_formula(int x, int y) {
    return x - y * (x / y);
}

int main() {
    std::chrono::steady_clock::time_point begin, end; // initializarea variabilelor de timp

    begin = std::chrono::steady_clock::now(); // momentul in care incepe executia codului
    for (int i = 0; i < number_of_tests; ++i) {
        calc_remainder_with_repeated_substractions(1e5, 7); // codul pe care dorim sa-l rulam si sa vedem cat dureaza
    }
    end = std::chrono::steady_clock::now(); // momentul in care se termina executia codului
    std::cout << "calc_remainder_with_repeated_substractions: " << std::chrono::duration_cast<std::chrono::microseconds>(end - begin).count() << "ms\n\n"; // diferenta de timp

    begin = std::chrono::steady_clock::now();
    for (int i = 0; i < number_of_tests; ++i) {
        calc_remainder_with_math_formula(1e5, 7);
    }
    end = std::chrono::steady_clock::now();
    std::cout << "calc_remainder_with_math_formula: " << std::chrono::duration_cast<std::chrono::microseconds>(end - begin).count() << "ms\n\n";

    return 0;
}

Console:

calc_remainder_with_repeated_substractions: 2339667ms

calc_remainder_with_math_formula: 2495ms

Observam ca daca vrem sa aflam de 10.000 de ori restul impartirii numarului 10.000 la 7 cu prima metoda, avem nevoie de 2.3396s pe cand daca folosim a 2-a metoda, observam o crestere in performanta, codul ruland in 0.0024s.

 

Prima metoda este inspirata din acest tutorial.

Edited by Vesca
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