C++11: chrono
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chronoはtime-libraryで、chronoというライブラリを使用するにはincludeが必要です.
通常chronoというライブラリを使用するにはratioというライブラリが欠かせない、#includeを含める必要があり、すでに#includeがある場合は#includeを必要としない.
まず2つの概念を明らかにします.
duration(期間):ある時間単位における明確なtick(一時数)を指す.例を挙げると、「3分」は「3個1分」を指す.
timepointとは、durationとepoch(開始点)の組み合わせを意味する.典型的な例は、「1970年1月1日からの第1 262 300 400秒」と記述される「2000年新年真夜中」時点である.
ratio:
通常chronoというライブラリを使用するにはratioというライブラリが欠かせない、#include
まず2つの概念を明らかにします.
duration(期間):ある時間単位における明確なtick(一時数)を指す.例を挙げると、「3分」は「3個1分」を指す.
timepointとは、durationとepoch(開始点)の組み合わせを意味する.典型的な例は、「1970年1月1日からの第1 262 300 400秒」と記述される「2000年新年真夜中」時点である.
ratio:
template <intmax_t Numerator, intmax_t Denominator = 1> class ratio;
Numerator: .
Denominator: .
ratio :
ratio::num; // ratio .
ratio::den; // ratio .
#include <iostream>
#include <ratio>
int main()
{
std::ratio<1, 4> oneForth;
std::cout<<"Numrator: "<<oneForth.num<<std::endl; // : 1.
std::cout<<"Denominator: "<<oneForth.den<<std::endl; // : 4.
return 0;
}
std::chrono::duration
.
template <class Rep, class Period = ratio<1> >
class duration;
Rep: (int, double....), .
Period: std::ratio .
:
std::chrono::duration<int, std::ratio<1,1>> seconds(3);//3 .
duration ( std::duration, std::ratio ) :
template <class ToDuration, class Rep, class Period>
constexpr ToDuration duration_cast (const duration<Rep,Period>& dtn);
ToDuration: duration .
Rep: duration .
Period: duration std::ratio .
duration :
constexpr rep count() const;
duration std::ratio .
static constexpr duration zero();
0 duration.
static constexpr duration min();
.
static constexpr duration zero();
.
#include <iostream>
#include <ratio>
#include <chrono>
int main()
{
using second_type = std::chrono::duration<int, std::ratio<1, 1>>;
using minutes_type = std::chrono::duration<int, std::ratio<60, 1>>;
using hour_type = std::chrono::duration<int, std::ratio<3600, 1>>;
second_type oneDay1(24*3600); // ：24*3600 .
minutes_type oneDay2(24*60); // : 24*60 .
hour_type oneDay3(24); // ： 24 .
//hour_type oneDay4(oneDay2); //error. .
hour_type oneDay5(oneDay3); // ok.
hour_type oneDay6(std::chrono::duration_cast<hour_type>(oneDay2)); //ok.
std::cout<< oneDay3.count() <<std::endl; // ： 24.
hour_type threeDay = oneDay3 * 3; // 3 : 3*24
std::cout<< threeDay.count() <<std::endl;// : 3 * 24.
std::chrono::steady_clock::time_point t1 = std::chrono::steady_clock::now(); // .
std::cout<< "Print something..."<<std::endl;
std::chrono::steady_clock::time_point t2 = std::chrono::steady_clock::now(); // .
std::chrono::steady_clock::duration d = t2 - t1; // std::cout<<"Print something..."<<std::endl; .
// steady_clock duration.
if(d == std::chrono::steady_clock::duration::zero()){ // 0.
std::cout<<"The interal clock did not tick
"<<std::endl;
}else{
std::cout<<"The interal clock advanced! "<< d.count() <<std::endl;
}
using namespace std::chrono;
milliseconds ms(7255042);
hours hh = duration_cast<hours>(ms);
minutes mm = duration_cast<minutes>(ms % hours(1)); // ms std::chrono::milliseconds .
seconds ss = duration_cast<seconds>(ms % minutes(1));
std::cout<<"hours: "<<hh.count()<<" minutes: "<<mm.count()<<" seconds: "<<ss.count()<<std::endl;
return 0;
}
Clock:
Clock epoch( ) tick( ， period). Clock (tick) （millionsecond）， UNIX epoch( ): 1970 1 1 , (tick) (nanosecond), .
Clock “ Clock ” timepoint ， Clock now() “ ” timepoint .
Clock( ） ：
std::system_clock; // timepoint( ) . clock to_time_t() from_time_t(), timepoint C time_t 。
std::steady_clock; // 。 ， timepoint ， timepoint .
std::high_resolution_clock; // tick( ） clock.( 1 ).
， clock , epoch( ), " timepoint "
3 Clock :
Clock::duration // Clock duration( ) . Clock .
Clock::rep // duration :double ，int ， , :Clock::duration::rep
Clock::period // Clock duration ， ， ？ ？ std::ratio .
Clock::duration::period.
Clock::is_steady // Clock steady ， true.
Clock::now() // static ， .
#include <iostream>
#include <chrono>
#include <type_traits>
template<typename Clock, typename = typename std::enable_if< std::is_same<Clock, std::chrono::steady_clock>::value
|| std::is_same<Clock, std::chrono::system_clock>::value
|| std::is_same<Clock, std::chrono::high_resolution_clock>::value
>::type>
void printClockData()
{
std::cout<<"- precision: ";
using P = typename Clock::period; // Clock::duration::period; std::ratio .
if(std::ratio_less_equal<P, std::milli>::value){
using TT = typename std::ratio_multiply<P, std::kilo>::type; // type std::ratio .
std::cout<< std::fixed << double(TT::num)/TT::den << " milliseconds " << std::endl;
}else{
std::cout<< std::fixed << double(P::num)/P::den <<" seconds"<<std::endl;
}
std::cout<<"- is_steady: "<< std::boolalpha << Clock::is_steady << std::endl;
}
int main()
{
std::cout<< "system_clock: " <<std::endl;
printClockData<std::chrono::system_clock>();
std::chrono::system_clock::time_point t1 = std::chrono::system_clock::now();
std::cout<< "system_clock::now() "<<std::endl;
std::chrono::system_clock::duration sd = std::chrono::system_clock::now() - t1;
std::cout<< "cost: "<< sd.count() <<std::endl; // : 0
std::cout<< "
high_resolution_clock: "<<std::endl;
printClockData<std::chrono::high_resolution_clock>();
std::chrono::high_resolution_clock::time_point t2 = std::chrono::high_resolution_clock::now();
std::cout<< "high_resolution_clock::now() " <<std::endl;
std::chrono::high_resolution_clock::duration hd = std::chrono::high_resolution_clock::now() - t2;
std::cout<< "cost: "<< hd.count() <<std::endl; // : 0
std::cout<< "
steady_clock: "<<std::endl;
printClockData<std::chrono::steady_clock>();
std::chrono::steady_clock::time_point t3 = std::chrono::steady_clock::now();
std::cout<< "steady_clock::now() "<<std::endl;
std::chrono::steady_clock::duration ssd = std::chrono::steady_clock::now() - t3;
std::cout<<"cost: "<< ssd.count() <<std::endl;
std::chrono::duration<std::chrono::steady_clock::rep, std::chrono::steady_clock::period> du = ssd;
std::chrono::steady_clock::period ratioForSteady_clock;
std::cout<< ratioForSteady_clock.num << " " << ratioForSteady_clock.den <<std::endl;
return 0;
}
Timepoint( ):
（ ） clock， clock， timepoint。Class time_point ， clock .
template <class Clock, class Duration = typename Clock::duration>
class time_point;
4 timepoint .
1,Epoch, clock time_point default .
2,Current time, clock static now() .
3,Minimnum timepoint, clock timepoint static min() .
4,Maximum timepoint, clocktimepoint static max() .
#include <iostream>
#include <chrono>
#include <ctime>
#include <string>
std::string asString(const std::chrono::system_clock::time_point& tp)
{
std::time_t t = std::chrono::system_clock::to_time_t(tp);
std::string timeString = std::asctime(std::gmtime(&t));
//timeString.resize(timeString.size()-1);
return timeString;
}
int main()
{
std::chrono::system_clock::time_point tp;
std::cout<< "epoch: "<< asString(tp) <<std::endl;
tp = std::chrono::system_clock::now();
std::cout<< "now: "<< asString(tp) <<std::endl;
/*tp = std::chrono::system_clock::time_point::min();
std::cout<< "min: "<< asString(tp) <<std::endl;*/ // (timepoint).
// std::chrono::time_point_cast;
using userDefined = std::chrono::time_point<std::chrono::system_clock, std::chrono::duration<int, std::micro>>;
userDefined tp1 = std::chrono::time_point_cast<std::chrono::duration<int, std::micro>>(std::chrono::system_clock::time_point::min());
std::cout<< "min: "<< asString(tp1) <<std::endl;
// std::chrono::time_point .
std::chrono::time_point<std::chrono::system_clock, std::chrono::duration<int>> t_p;
std::chrono::system_clock::time_point tp2(t_p);
tp2 = std::chrono::system_clock::time_point::max();
std::cout<< "max: "<< asString(tp2)<<std::endl;
return 0;
}
std::chrono::time_point operator(s):
#include <iostream>
#include <ctime>
#include <chrono>
#include <string>
std::string asString(const std::chrono::system_clock::time_point& tp)
{
std::time_t t = std::chrono::system_clock::to_time_t(tp);
std::string timeString(std::ctime(&t));
return timeString;
}
int main()
{
using Days = std::chrono::duration<int, std::ratio<3600*24>>;
using Hours = std::chrono::duration<int, std::ratio<3600>>;
using Minutes = std::chrono::duration<int, std::ratio<60>>;
using Seconds = std::chrono::duration<int, std::ratio<1,1>>;
using Years = std::chrono::duration<unsigned long long, std::ratio<3600*24*365>>;
std::chrono::time_point<std::chrono::system_clock> tp1;
std::cout<< "Epoch: "<< asString(tp1) <<std::endl; // : asString(std::chrono::system_clock::time_point());
// 1 ，23 ，55 .
tp1 += Days(1) + Hours(23) + Minutes(55);
std::cout<<"Later: " << asString(tp1) << std::endl;
std::chrono::duration<std::chrono::system_clock::rep, std::chrono::system_clock::period> dis = tp1 - std::chrono::system_clock::time_point();
// ： std::chrono::system_clock::time_point(); Epoch.
std::cout<< "Diff: "
<< (std::chrono::duration_cast<std::chrono::minutes>(dis)).count()
<< " minute(s)." <<std::endl;
Days days = std::chrono::duration_cast<Days>(dis);
std::cout<< "days: "
<< days.count() << " day(s)."<<std::endl;
tp1 -= Days(365); // .
std::cout<< "-1 year: " << asString(tp1) <<std::endl;
tp1 -= Years(50); // .
std::cout<< "-50 years: " << asString(tp1) <<std::endl;
tp1 -= Years(50); // .
std::cout<< "again -50 years: " << asString(tp1) <<std::endl;
return 0;
}