Timer.h

#pragma once
 
#include <chrono>
#include <sstream>
#include <time.h>
 
typedef std::chrono::time_point<std::chrono::system_clock> TimePoint;
 
class Timer
{
public:
    Timer();
    explicit Timer(const double begin_time);
    virtual ~Timer() = default;
 
    double elapsed() const;
    void restart();
 
private:
    TimePoint _start;
    double _begin_time = 0;
};
 
inline Timer::Timer()
{
    restart();
}
 
inline Timer::Timer(const double begin_time):
    _begin_time(begin_time)
{
    // _start
    restart();
}
 
inline void Timer::restart()
{
    _start = std::chrono::system_clock::now();
}
 
inline double Timer::elapsed() const
{
    return std::chrono::duration<double>(std::chrono::system_clock::now() - _start).count()
           + _begin_time;
}
 
inline std::string format_time_str(const long int time_in_seconds)
{
    std::time_t seconds(time_in_seconds); // you have to convert your input_seconds into time_t
    std::tm p;
 
    // convert to broken down time
#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__NT__)
    gmtime_s(&p, &seconds);
#else // defined(__unix__) || (__APPLE__)
    gmtime_r(&seconds, &p);
#endif
    std::stringstream ss;
    const auto days = p.tm_yday;
    const auto hours = p.tm_hour;
    const auto mins = p.tm_min;
    const auto secs = p.tm_sec;
    if (days > 0)
    {
        ss << days << " days ";
    }
    if (hours > 0)
    {
        ss << hours << " hours ";
    }
    if (mins > 0)
    {
        ss << mins << " minutes ";
    }
    if (secs > 0)
    {
        ss << secs << " seconds ";
    }
    return ss.str();
}