template <class Rep, 
class Period = ratio<1> >
class duration;

template <intmax_t N, 
intmax_t D = 1
> class ratio;

ratio<2>	//代表2秒
ratio<60>	//代表1分鐘
ratio<60*60>	//代表1小時(shí)
ratio<60*60*24>	//代表1天
ratio<1, 1000>	//代表1毫秒
ratio<1, 1000000>	//代表1微秒
ratio<1, 1000000000>	//代表1納秒

typedef duration<long long, nano> nanoseconds;
typedef duration<long long, micro> microseconds;
typedef duration<long long, milli> milliseconds;
typedef duration<long long> seconds;
typedef duration<int, ratio<60> > minutes;
typedef duration<int, ratio<3600> > hours;

//休眠100毫秒
this_thread::sleep_for(std::chrono::duration<int, ratio<1, 100>>(100));
this_thread::sleep_for(std::chrono::microseconds(100));//更簡(jiǎn)單

//休眠3秒
this_thread::sleep_for(std::chrono::duration<int>(3));
this_thread::sleep_for(std::chrono::seconds(3));//更簡(jiǎn)單

#include<iostream>
#include<chrono>
int main()
{
	std::chrono::seconds s(3);//3秒
	std::chrono::milliseconds ms = 2 * s;//6000毫秒
	std::cout << "3 s duration has " << s.count() << " ticks\n" << "6000 ms duration has " << ms.count() << " ticks\n";
}

int main()
{
	//目標(biāo)duration的Rep為double
	std::chrono::milliseconds int_milliseconds(1024);       // 1024ms
	std::chrono::microseconds int_microseconds(1024);       // 1024us
	std::chrono::duration<double> double_seconds;
	double_seconds = int_microseconds;	//1024ms = 1.024s
	double_seconds = int_milliseconds;	//1024us = 0.001024s


	//當(dāng)duration的Rep都為整型，且源Period可被目標(biāo)Period整除時(shí)
	int_microseconds = int_milliseconds; //ms賦值給us可以，但是us賦值給ms不可
	int_milliseconds = std::chrono::seconds(1);	//s賦值給ms可以，但是ms賦值給s不可以


	//源duration的Rep為double， 目標(biāo)duration的Rep不為double，不能轉(zhuǎn)換
	//std::chrono::milliseconds t1 = std::chrono::duration<double>(1024);

/*
 * 數(shù)據(jù)會(huì)發(fā)生截?cái)鄷r(shí)的轉(zhuǎn)化
 * chrono庫(kù)提供了duration之間相互轉(zhuǎn)化的函數(shù)，其定義如下
 *      template <class ToDuration, class Rep, class Period>
 *      constexpr ToDuration duration_cast(const duration<Rep,Period>& d);
*/
    std::chrono::seconds t1 = std::chrono::duration_cast<std::chrono::seconds>(std::chrono::milliseconds(1024));               // 1s = 1024ms(精度損失)
    std::chrono::seconds t2 = std::chrono::duration_cast<std::chrono::seconds>(std::chrono::duration<double>(1.024));          // 1s = 1.024s 
}

int main()
{
	std::chrono::minutes t1(10);
	std::chrono::seconds t2(50);
	std::chrono::seconds t3 = t1 - t2;
	cout << t3.count() << " second" << endl;
}

int main()
{
	std::chrono::duration<double, std::ratio<9, 7>> d1(3);
	std::chrono::duration<double, std::ratio<6, 5>> d2(1);
	auto d3 = d1 - d2;
	cout << "d3類型 : "<<typeid(d3).name() << endl;
	cout << d3.count() << endl;
}

template <class Clock, 
class Duration = typename Clock::duration>
class time_point;

template <class Clock, 
class Duration = typename Clock::duration>
class time_point;

#include<iostream>
#include<chrono>
#include<ratio>
using namespace std::chrono;
int main()
{
	using days_type = duration<int, std::ratio<60 * 60 * 24>>;
	time_point<system_clock, days_type> today = time_point_cast<days_type>(system_clock::now());
	std::cout << today.time_since_epoch().count() << " days since epoch" << endl;
}

#include<iostream>
#include<chrono>
#include<iomanip>
using namespace std::chrono;
int main()
{
	system_clock::time_point now = system_clock::now();
	std::time_t prev = system_clock::to_time_t(now - hours(24)); //返回時(shí)間戳
	std::time_t next = system_clock::to_time_t(now + hours(24)); //返回時(shí)間戳

	cout << "One day ago, the time was " << std::put_time(std::localtime(&prev), "%Y.%m.%d %H:%M:%S") << endl;
	cout << "A day later, the time is " << std::put_time(std::localtime(&next), "%Y.%m.%d %H:%M:%S") << endl;	 
}

int main()
{
	std::chrono::system_clock::time_point t1 = std::chrono::system_clock::now();
	cout << "hello fl" << endl;
	std::chrono::system_clock::time_point t2 = std::chrono::system_clock::now();
	cout << (t2 - t1).count() << " tick count" << endl;
	return 0;
}

std::time_t now_c = std::chrono::system_clock::to_time_t(time_point);