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Defined in header <chrono> | ||
template< class Rep, | (since C++11) | |
Class templatestd::chrono::duration represents a time interval.
It consists of a count of ticks of typeRep and a tick period, where the tick period is a compile-time rationalfraction representing the time in seconds from one tick to the next.
The only data stored in aduration is a tick count of typeRep. IfRep is floating point, then theduration can represent fractions of ticks.Period is included as part of the duration's type, and is only used when converting between different durations.
Contents |
| Member type | Definition |
rep | Rep, an arithmetic type, or a class emulating an arithmetic type, representing the number of ticks |
period | Period(until C++17)typename Period::type(since C++17), astd::ratio representing the tick period (i.e. the number of second's fractions per tick) |
| constructs new duration (public member function)[edit] | |
| assigns the contents (public member function)[edit] | |
| returns the count of ticks (public member function)[edit] | |
[static] | returns the special duration value zero (public static member function)[edit] |
[static] | returns the special duration value min (public static member function)[edit] |
[static] | returns the special duration value max (public static member function)[edit] |
| implements unary + and unary - (public member function)[edit] | |
| increments or decrements the tick count (public member function)[edit] | |
| implements compound assignment between two durations (public member function)[edit] |
| implements arithmetic operations with durations as arguments (function template)[edit] | |
(C++11)(C++11)(removed in C++20)(C++11)(C++11)(C++11)(C++11)(C++20) | compares two durations (function template)[edit] |
(C++11) | converts a duration to another, with a different tick interval (function template)[edit] |
(C++17) | converts a duration to another, rounding down (function template)[edit] |
(C++17) | converts a duration to another, rounding up (function template)[edit] |
(C++17) | converts a duration to another, rounding to nearest, ties to even (function template)[edit] |
(C++17) | obtains the absolute value of the duration (function template)[edit] |
(C++20) | performs stream output on aduration(function template)[edit] |
(C++20) | parses aduration from a stream according to the provided format(function template)[edit] |
A type/* intXX */ used in the table below means a signed integer type of at least XX bits.
| Type | Definition |
std::chrono::nanoseconds | std::chrono::duration</* int64 */,std::nano> |
std::chrono::microseconds | std::chrono::duration</* int55 */,std::micro> |
std::chrono::milliseconds | std::chrono::duration</* int45 */,std::milli> |
std::chrono::seconds | std::chrono::duration</* int35 */> |
std::chrono::minutes | std::chrono::duration</* int29 */,std::ratio<60>> |
std::chrono::hours | std::chrono::duration</* int23 */,std::ratio<3600>> |
std::chrono::days(since C++20) | std::chrono::duration</* int25 */,std::ratio<86400>> |
std::chrono::weeks(since C++20) | std::chrono::duration</* int22 */,std::ratio<604800>> |
std::chrono::months(since C++20) | std::chrono::duration</* int20 */,std::ratio<2629746>> |
std::chrono::years(since C++20) | std::chrono::duration</* int17 */,std::ratio<31556952>> |
Note: each of the predefined duration types up tohours covers a range of at least ±292 years.
Each of the predefined duration types | (since C++20) |
| specializes thestd::common_type trait (class template specialization)[edit] | |
(C++11) | indicates that a duration is convertible to duration with different tick period (class template)[edit] |
(C++11) | constructs zero, min, and max values of a tick count of given type (class template)[edit] |
formatting support forduration(class template specialization)[edit] | |
| hash support forstd::chrono::duration (class template specialization) |
template<class Rep,class Period> constexprbool enable_nonlocking_formatter_optimization<chrono::duration<Rep, Period>> | (since C++23) | |
This specialization ofstd::enable_nonlocking_formatter_optimization enables efficient implementation ofstd::print andstd::println for printing achrono::duration object when the template parameterRep enables it.
Defined in inline namespace std::literals::chrono_literals | |
(C++14) | astd::chrono::duration literal representing hours (function)[edit] |
(C++14) | astd::chrono::duration literal representing minutes (function)[edit] |
(C++14) | astd::chrono::duration literal representing seconds (function)[edit] |
(C++14) | astd::chrono::duration literal representing milliseconds (function)[edit] |
(C++14) | astd::chrono::duration literal representing microseconds (function)[edit] |
(C++14) | astd::chrono::duration literal representing nanoseconds (function)[edit] |
Note: the literal suffixes | (since C++20) |
The actual time interval (in seconds) that is held by a duration objectd is roughly equal tod.count()* D::period::num/ D::period::den, whereD is of typechrono::duration<> andd is an object of such type.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_chrono_udls | 201304L | (C++14) | User-defined literals for time types |
This example shows how to define several custom duration types and convert between types:
#include <chrono>#include <iostream> usingnamespace std::chrono_literals; template<typename T1,typename T2>using mul=std::ratio_multiply<T1, T2>; int main(){using microfortnights= std::chrono::duration<float, mul<mul<std::ratio<2>, std::chrono::weeks::period>,std::micro>>;using nanocenturies= std::chrono::duration<float, mul<mul<std::hecto, std::chrono::years::period>,std::nano>>;using fps_24= std::chrono::duration<double,std::ratio<1,24>>; std::cout<<"1 second is:\n"; // integer scale conversion with no precision loss: no caststd::cout<< std::chrono::milliseconds(1s).count()<<" milliseconds\n"<< std::chrono::microseconds(1s).count()<<" microseconds\n"<< std::chrono::nanoseconds(1s).count()<<" nanoseconds\n"; // integer scale conversion with precision loss: requires a caststd::cout<<std::chrono::duration_cast<std::chrono::minutes>(1s).count()<<" minutes\n";// alternative to duration_cast:std::cout<< 1s/ 1min<<" minutes\n"; // floating-point scale conversion: no caststd::cout<< microfortnights(1s).count()<<" microfortnights\n"<< nanocenturies(1s).count()<<" nanocenturies\n"<< fps_24(1s).count()<<" frames at 24fps\n";}
Output:
1 second is:1000 milliseconds1000000 microseconds1000000000 nanoseconds0 minutes0 minutes0.82672 microfortnights0.316887 nanocenturies24 frames at 24fps
