std::chrono::weekday::operator[]

 

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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)
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C 风格日期和时间

 

std::chrono::weekday

成员函数

weekday::weekday

weekday::operator++weekday::operator--

weekday::operator+=weekday::operator-=

weekday::c_encodingweekday::iso_encoding

weekday::ok

weekday::operator[]

非成员函数

operator==

operator+operator-

operator<<

from_stream

辅助类

formatter<std::chrono::weekday>

formatter<std::chrono::hash> (C++26)

 

constexpr std::chrono::weekday_indexed     operator[]( unsigned index ) const noexcept;	(1)	(C++20 起)
constexpr std::chrono::weekday_last     operator[]( std::chrono::last_spec ) const noexcept;	(2)	(C++20 起)

1) 从 *this 和 index 构造 weekday_indexed。结果表示在某个待指定月份中的第 index 个星期之日。若 index 不在范围 [​0​, 7] 中或若 !ok()，则结果中保有的值（底层星期之日和索引）未指定。

2) 从 *this 构造 weekday_last。结果表示某个待指定月份中的最后一个星期之日。

返回值

1) std::chrono::weekday_indexed(*this, index)

2) std::chrono::weekday_last(*this)

示例

运行此代码

#include <chrono>
#include <iostream>
using namespace std::chrono;
 
int main()
{
    constexpr auto second_tuesday_in_October_2019 =
        year_month_day{Tuesday[2] / October / 2019y};
 
    constexpr auto last_tuesday_in_October_2019 =
        year_month_day{Tuesday[last] / October / 2019y};
 
    std::cout << second_tuesday_in_October_2019 << '\n'
              << last_tuesday_in_October_2019 << '\n'; 
}

可能的输出：

2019-10-08
2019-10-29