For easy benchmarking - Timer object that show time when is destroyed.

timer.cpp

#include <chrono>

// ------------------------------------------
// Timer
// ------------------------------------------
struct Timer {
    using clock = std::chrono::high_resolution_clock;
    using unit = std::chrono::duration<double, std::nano>;
private:
    std::string_view msg;
    std::chrono::time_point<clock> ini;
public:
    Timer(std::string_view msg = ""): msg(msg), ini(clock::now()) {}
    ~Timer(){
        std::cout << "[TIMER] - " << msg << ((msg == "")? "":" : ")
                  << unit(clock::now() - ini).count() << " ns" << "\n";
    }
};
// ------------------------------------------

/*
USAGE EXAMPLE:

switch (input) {
    case 0:{
        Timer t;
        // <first task>
        }break;

    case 1:{
        Timer t("[1]");
        // <second task>
    }break;

    default:{
        Timer t("[Fail]");
        std::cout << "[!] - Undefined input!" << "\n";
        }break;
}
*/