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

 

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通用工具 日期和时间 函数对象 格式化库 (C++20) bitset hash (C++11) 关系运算符 (C++20 中已弃用) rel_ops::operator!=rel_ops::operator>     rel_ops::operator<=rel_ops::operator>= 整数比较函数 cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)    cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) 交换 和 类型操作 swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) 通用词汇类型 pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23) 基本字符串转换 to_chars (C++17) from_chars (C++17) chars_format (C++17) to_chars_result (C++17) from_chars_result (C++17)

 

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std::chrono::duration

成员函数
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%=
非成员函数
operator+operator-operator*operator/operator% operator==operator!=operator<operator<=operator>operator>=operator<=> (直到 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)
辅助类
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)	(自 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)	(自 C++11 起) (直到 C++20)
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)	(自 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)	(自 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)	(自 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)	(自 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)	(自 C++20 起)

比较两个持续时间。令 CT 为 std::common_type<std::chrono::duration<Rep1, Period1>, std::chrono::duration<Rep2, Period2>>::type

1,2) 检查 lhs 和 rhs 是否相等，即对两种持续时间通用的类型来说，刻度数是否相等。

3-6) 比较 lhs 与 rhs，即对两种持续时间通用的类型来说，比较刻度数。

7) 将 lhs 与 rhs 进行比较，即比较两种持续时间类型的刻度数量。返回类型根据 CT(lhs).count() <=> CT(rhs).count() 推断。

!= 运算符是由 operator== 合成 的。

(自 C++20 起)

参数

lhs	-	运算符左侧的持续时间
rhs	-	运算符右侧的持续时间

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

运行此代码

#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);
}

输出

2s == 2000ms
61s > 1min