operator==,!=,<,<=,>,>=,<=>(std::chrono::duration)

 

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日曆 day (C++20) month (C++20) year (C++20) weekday (C++20) operator/ (C++20) year_month_day (C++20) year_month_day_last (C++20) year_month_weekday (C++20) year_month_weekday_last (C++20)   weekday_indexed (C++20) weekday_last (C++20) month_day (C++20) month_day_last (C++20) month_weekday (C++20) month_weekday_last (C++20) year_month (C++20) last_speclast (C++20)(C++20) chrono I/O parse (C++20)

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std::chrono::duration

成員函式
duration::duration duration::operator= duration::count duration::zero duration::min duration::max duration::operator+duration::operator-	duration::operator++duration::operator-- duration::operator+=duration::operator-=duration::operator*=duration::operator/=duration::operator%=
非成員函式
operator+operator-operator*operator/operator% operator==operator!=operator<operator<=operator>operator>=operator<=> (until C++20)(C++20) operator<< (C++20)	duration_cast floor (C++17) ceil (C++17) round (C++17) abs (C++17) operator""h (C++14) operator""min (C++14) operator""s (C++14) operator""ms (C++14) operator""us (C++14) operator""ns (C++14) from_stream (C++20)
輔助類
common_type treat_as_floating_point      duration_values	formatter<std::chrono::duration> (C++20) hash<std::chrono::duration> (C++26)

 

template< class Rep1, class Period1, class Rep2, class Period2 > constexpr bool operator==( const std::chrono::duration<Rep1, Period1>& lhs,                            const std::chrono::duration<Rep2, Period2>& rhs );	(1)	(C++11 起)
template< class Rep1, class Period1, class Rep2, class Period2 > constexpr bool operator!=( const std::chrono::duration<Rep1, Period1>& lhs,                            const std::chrono::duration<Rep2, Period2>& rhs );	(2)	(C++11 起) (C++20 前)
template< class Rep1, class Period1, class Rep2, class Period2 > constexpr bool operator<( const std::chrono::duration<Rep1, Period1>& lhs,                           const std::chrono::duration<Rep2, Period2>& rhs );	(3)	(C++11 起)
template< class Rep1, class Period1, class Rep2, class Period2 > constexpr bool operator<=( const std::chrono::duration<Rep1, Period1>& lhs,                            const std::chrono::duration<Rep2, Period2>& rhs );	(4)	(C++11 起)
template< class Rep1, class Period1, class Rep2, class Period2 > constexpr bool operator>( const std::chrono::duration<Rep1, Period1>& lhs,                           const std::chrono::duration<Rep2, Period2>& rhs );	(5)	(C++11 起)
template< class Rep1, class Period1, class Rep2, class Period2 > constexpr bool operator>=( const std::chrono::duration<Rep1, Period1>& lhs,                            const std::chrono::duration<Rep2, Period2>& rhs );	(6)	(C++11 起)
template< class Rep1, class Period1, class Rep2, class Period2 >     requires std::three_way_comparable<std::common_type_t<Rep1, Rep2>> constexpr auto operator<=>( const std::chrono::duration<Rep1, Period1>& lhs,                             const std::chrono::duration<Rep2, Period2>& rhs );	(7)	(C++20 起)

比較兩個時長。令 CT 為 std::common_type<std::chrono::duration<Rep1, Period1>, std::chrono::duration<Rep2, Period2>>::type

1,2) 檢查 lhs 和 rhs 是否相等，即兩種時長共同型別的計時次數是否相等。

3-6) 比較 lhs 和 rhs，即比較兩種時長共同型別的計時次數。

7) 比較 lhs 和 rhs，即比較兩種時長共同型別的計時次數。返回型別從 CT(lhs).count() <=> CT(rhs).count() 推導。

!= 運算子由 operator== 合成。

(C++20 起)

引數

lhs	-	運算子左側的時長
rhs	-	運算子右側的時長

返回值

1) CT(lhs).count() == CT(rhs).count()

2) !(lhs == rhs)

3) CT(lhs).count() < CT(rhs).count()

4) !(rhs < lhs)

5) rhs < lhs

6) !(lhs < rhs)

7) CT(lhs).count() <=> CT(rhs).count()

示例

執行此程式碼

#include <chrono>
#include <iostream>
 
int main()
{
    constexpr auto t1 = std::chrono::seconds(2);
    constexpr auto t2 = std::chrono::milliseconds(2000);
 
    if constexpr (t1 == t2)
        std::cout << t1 << " == " << t2 << '\n';
    else
        std::cout << t1 << " != " << t2 << '\n';
 
    constexpr auto t3 = std::chrono::seconds(61);
    constexpr auto t4 = std::chrono::minutes(1);
 
    if constexpr (t3 > t4)
        std::cout << t3 << " > " << t4 << '\n';
    else
        std::cout << t3 << " <= " << t4 << '\n';
 
    using namespace std::chrono_literals;
 
    static_assert(1h == 60min);
    static_assert(1min == 60s);
    static_assert(1s == 1'000ms);
    static_assert(1ms == 1'000us);
    static_assert(1us == 1'000ns);
}

輸出

2s == 2000ms
61s > 1min