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

 

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std::chrono::duration

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common_type treat_as_floating_point duration_values formatter<std::chrono::duration> (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);	(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)

比较二个时长。 令 CT 为 std::common_type<std::chrono::duration<Rep1, Period1>, std::chrono::duration<Rep2, Period2>>::type ：

1-2) 检查 lhs 与 rhs 是否相等，即以两个 duration 的共用类型表示的计次数是否相等。

3-6) 比较 lhs 与 rhs ，即比较两个 duration 的共用类型表示的计次数。

7) 比较 lhs 与 rhs ，即比较两个 duration 的共用类型表示的计次数。从 CT(lhs).count() <=> CT(rhs).count() 推导返回类型。

!= 运算符从 operator== 合成。

(C++20 起)

参数

lhs	-	运算符左侧的 duration
rhs	-	运算符右侧的 duration

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()
{
    if(std::chrono::seconds(2) == std::chrono::milliseconds(2000))
        std::cout <<  "2 s == 2000 ms\n";
    else
        std::cout <<  "2 s != 2000 ms\n";
 
    if(std::chrono::seconds(61) > std::chrono::minutes(1))
        std::cout <<  "61 s > 1 min\n";
    else
        std::cout <<  "61 s <= 1 min\n";
 
}

输出：

2 s == 2000 ms
61 s > 1 min