Я решил, что хочу сравнить определенную функцию, поэтому янапишите код:

#include 
#include 

int SlowCalculation(int input) { ... }

int main() {
    std::cout < "Benchmark running..." < std::endl;
    std::clock_t start = std::clock();
    int answer = SlowCalculation(42);
    std::clock_t stop = std::clock();
    double delta = (stop - start) * 1.0 / CLOCKS_PER_SEC;
    std::cout < "Benchmark took " < delta < " seconds, and the answer was "
              < answer < '.' < std::endl;
    return 0;
}