operator==,!=,<,<=,>,>=,<=>(std::chrono::duration)
来自cppreference.com
template< class Rep1, class Period1, class Rep2, class Period2 > constexpr bool operator==( const std::chrono::duration<Rep1, Period1>& lhs, |
(1) | (C++11 起) |
template< class Rep1, class Period1, class Rep2, class Period2 > constexpr bool operator!=( const std::chrono::duration<Rep1, Period1>& lhs, |
(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, |
(3) | (C++11 起) |
template< class Rep1, class Period1, class Rep2, class Period2 > constexpr bool operator<=( const std::chrono::duration<Rep1, Period1>& lhs, |
(4) | (C++11 起) |
template< class Rep1, class Period1, class Rep2, class Period2 > constexpr bool operator>( const std::chrono::duration<Rep1, Period1>& lhs, |
(5) | (C++11 起) |
template< class Rep1, class Period1, class Rep2, class Period2 > constexpr bool operator>=( const std::chrono::duration<Rep1, Period1>& lhs, |
(6) | (C++11 起) |
template< class Rep1, class Period1, class Rep2, class Period2 > requires std::three_way_comparable<std::common_type_t<Rep1, Rep2>> |
(7) | (C++20 起) |
比较两个时长。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 的公共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 的公共类型表示的计次数。
7) 比较 lhs 与 rhs,即比较两个 duration 的公共类型表示的计次数。从 CT(lhs).count() <=> CT(rhs).count() 推导返回类型。
|
(C++20 起) |
参数
lhs | - | 运算符左侧的 duration
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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() { 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