Standard library header <chrono>

 

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Standard library headers

Language support <cfloat> <climits> <compare> (C++20) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)    <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) Concepts <concepts> (C++20) Diagnostics <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) Memory management <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) Metaprogramming <type_traits> (C++11) <ratio> (C++11)

General utilities <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) Containers <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <inplace_vector> (C++26)    <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> Iterators <iterator> Ranges <generator> (C++23) <ranges> (C++20)

Algorithms <algorithm> <numeric> Strings <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> Text processing <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)    Numerics <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <valarray> Time <chrono> (C++11) <ctime> C compatibility <ccomplex> (C++11/17/20*) <ciso646> (until C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

Input/output <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) Concurrency support <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) Execution support <execution> (C++17)

 

This header is part of the date and time library.

Classes

Defined in namespace std::chrono
duration (C++11)	a time interval (class template)
system_clock (C++11)	wall clock time from the system-wide realtime clock (class)
steady_clock (C++11)	monotonic clock that will never be adjusted (class)
high_resolution_clock (C++11)	the clock with the shortest tick period available (class)
time_point (C++11)	a point in time (class template)
treat_as_floating_point	indicates that a duration is convertible to duration with different tick period (class template)
duration_values	constructs zero, min, and max values of a tick count of given type (class template)
Convenience Typedefs
Defined in namespace std::chrono
std::chrono::nanoseconds	duration type with Period std::nano
std::chrono::microseconds	duration type with Period std::micro
std::chrono::milliseconds	duration type with Period std::milli
std::chrono::seconds	duration type with Period std::ratio<1>
std::chrono::minutes	duration type with Period std::ratio<60>
std::chrono::hours	duration type with Period std::ratio<3600>
Specializations
Defined in namespace std
std::common_type<std::chrono::duration> (C++11)	specializes the std::common_type trait (class template specialization)
std::common_type<std::chrono::time_point> (C++11)	specializes the std::common_type trait (class template specialization)

Functions

Duration
Defined in namespace std::chrono
operator+operator-operator*operator/operator% (C++11)	implements arithmetic operations with durations as arguments (function template)
operator==operator!=operator<operator<=operator>operator>=operator<=> (C++11)(C++11)(removed in C++20)(C++11)(C++11)(C++11)(C++11)(C++20)	compares two durations (function template)
duration_cast (C++11)	converts a duration to another, with a different tick interval (function template)
Time point
Defined in namespace std::chrono
operator+operator- (C++11)	performs add and subtract operations involving a time point (function template)
operator==operator!=operator<operator<=operator>operator>=operator<=> (C++11)(C++11)(removed in C++20)(C++11)(C++11)(C++11)(C++11)(C++20)	compares two time points (function template)
time_point_cast (C++11)	converts a time point to another time point on the same clock, with a different duration (function template)

Synospis

namespace std {
namespace chrono {
 
    // class template duration
    template <class Rep, class Period = ratio<1> > class duration;
 
    // class template time_point
    template <class Clock, class Duration = typename Clock::duration> class time_point;
 
} // namespace chrono
 
// common_type specializations
template <class Rep1, class Period1, class Rep2, class Period2>
    struct common_type<chrono::duration<Rep1, Period1>, chrono::duration<Rep2, Period2>>;
 
template <class Clock, class Duration1, class Duration2>
    struct common_type<chrono::time_point<Clock, Duration1>, chrono::time_point<Clock, Duration2>>;
 
namespace chrono {
 
    // customization traits
    template <class Rep> struct treat_as_floating_point;
    template <class Rep> struct duration_values;
 
    // duration arithmetic
    template <class Rep1, class Period1, class Rep2, class Period2>
        typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
        constexpr operator+(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    template <class Rep1, class Period1, class Rep2, class Period2>
        typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
        constexpr operator-(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    template <class Rep1, class Period, class Rep2>
        duration<typename common_type<Rep1, Rep2>::type, Period>
        constexpr operator*(const duration<Rep1, Period>& d, const Rep2& s);
    template <class Rep1, class Rep2, class Period>
        duration<typename common_type<Rep1, Rep2>::type, Period>
        constexpr operator*(const Rep1& s, const duration<Rep2, Period>& d);
    template <class Rep1, class Period, class Rep2>
        duration<typename common_type<Rep1, Rep2>::type, Period>
        constexpr operator/(const duration<Rep1, Period>& d, const Rep2& s);
    template <class Rep1, class Period1, class Rep2, class Period2>
        typename common_type<Rep1, Rep2>::type
        constexpr operator/(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
    template <class Rep1, class Period, class Rep2>
        duration<typename common_type<Rep1, Rep2>::type, Period>
        constexpr operator%(const duration<Rep1, Period>& d, const Rep2& s);
    template <class Rep1, class Period1, class Rep2, class Period2>
        typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
        constexpr operator%(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
 
    // duration comparisons
    template <class Rep1, class Period1, class Rep2, class Period2>
        constexpr bool operator==(const duration<Rep1, Period1>& lhs,
                                    const duration<Rep2, Period2>& rhs);
    template <class Rep1, class Period1, class Rep2, class Period2>
        constexpr bool operator!=(const duration<Rep1, Period1>& lhs,
                                    const duration<Rep2, Period2>& rhs);
    template <class Rep1, class Period1, class Rep2, class Period2>
        constexpr bool operator< (const duration<Rep1, Period1>& lhs,
                                    const duration<Rep2, Period2>& rhs);
    template <class Rep1, class Period1, class Rep2, class Period2>
        constexpr bool operator<=(const duration<Rep1, Period1>& lhs,
                                    const duration<Rep2, Period2>& rhs);
    template <class Rep1, class Period1, class Rep2, class Period2>
        constexpr bool operator> (const duration<Rep1, Period1>& lhs,
                                    const duration<Rep2, Period2>& rhs);
    template <class Rep1, class Period1, class Rep2, class Period2>
        constexpr bool operator>=(const duration<Rep1, Period1>& lhs,
                                    const duration<Rep2, Period2>& rhs);
 
    // duration_cast 
    template <class ToDuration, class Rep, class Period> 
        constexpr ToDuration duration_cast(const duration<Rep, Period>& d); 
 
    // convenience typedefs 
    typedef duration</*signed integer type of at least 64 bits*/, nano>        nanoseconds;
    typedef duration</*signed integer type of at least 55 bits*/, micro>       microseconds;
    typedef duration</*signed integer type of at least 45 bits*/, milli>       milliseconds;
    typedef duration</*signed integer type of at least 35 bits*/ >             seconds;
    typedef duration</*signed integer type of at least 29 bits*/, ratio< 60>>  minutes; 
    typedef duration</*signed integer type of at least 23 bits*/, ratio<3600>> hours; 
 
    // time_point arithmetic
    template <class Clock, class Duration1, class Rep2, class Period2>
        time_point<Clock, typename common_type<Duration1, duration<Rep2, Period2>>::type>
        operator+(const time_point<Clock, Duration1>& lhs, const duration<Rep2, Period2>& rhs);
    template <class Rep1, class Period1, class Clock, class Duration2>
        time_point<Clock, typename common_type<duration<Rep1, Period1>, Duration2>::type>
        operator+(const duration<Rep1, Period1>& lhs, const time_point<Clock, Duration2>& rhs);
    template <class Clock, class Duration1, class Rep2, class Period2>
        time_point<Clock, typename common_type<Duration1, duration<Rep2, Period2>>::type>
        operator-(const time_point<Clock, Duration1>& lhs, const duration<Rep2, Period2>& rhs);
    template <class Clock, class Duration1, class Duration2>
        typename common_type<Duration1, Duration2>::type
        operator-(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
 
    // time_point comparisons
    template <class Clock, class Duration1, class Duration2>
        bool operator==(const time_point<Clock, Duration1>& lhs,
                        const time_point<Clock, Duration2>& rhs);
    template <class Clock, class Duration1, class Duration2>
        bool operator!=(const time_point<Clock, Duration1>& lhs,
                        const time_point<Clock, Duration2>& rhs);
    template <class Clock, class Duration1, class Duration2>
        bool operator< (const time_point<Clock, Duration1>& lhs,
                        const time_point<Clock, Duration2>& rhs);
    template <class Clock, class Duration1, class Duration2>
        bool operator<=(const time_point<Clock, Duration1>& lhs,
                        const time_point<Clock, Duration2>& rhs);
    template <class Clock, class Duration1, class Duration2>
        bool operator> (const time_point<Clock, Duration1>& lhs,
                        const time_point<Clock, Duration2>& rhs);
    template <class Clock, class Duration1, class Duration2>
        bool operator>=(const time_point<Clock, Duration1>& lhs,
                        const time_point<Clock, Duration2>& rhs);
 
    // time_point_cast
    template <class ToDuration, class Clock, class Duration>
        time_point<Clock, ToDuration> time_point_cast(const time_point<Clock, Duration>& t);
 
    // clocks
    class system_clock;
    class steady_clock;
    class high_resolution_clock;
 
} // namespace chrono
}// namespace std