std::chrono::weekday::weekday
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std::chrono::weekday
Member functions
weekday::weekday
Nonmember functions
Helper classes
(C++26)
weekday() = default;
(1)
(since C++20)
constexpr explicit weekday( unsigned wd ) noexcept;
(2)
(since C++20)
constexpr weekday( const std::chrono::sys_days & sd ) noexcept;
(3)
(since C++20)
constexpr explicit weekday( const std::chrono::local_days & ld ) noexcept;
(4)
(since C++20)
Constructs a weekday object.
1) Default constructor leaves the weekday value uninitialized.
2) Constructs a
weekday object holding the weekday value wd. If wd == 7, the value held is 0. If wd > 255, the value held is unspecified.3) Constructs a
weekday object representing the day of the week sd corresponds to. This constructor defines an implicit conversion from std::chrono::sys_days to weekday.4) Constructs a
weekday object representing the day of the week ld corresponds to, as if by weekday(std::chrono::sys_days (ld.time_since_epoch())).[edit] Parameters
wd
-
a weekday value
sd
-
a system days object
ld
-
a local days object
[edit] Example
Run this code
#include <chrono> #include <iomanip> #include <iostream> int main() { constexpr std::chrono::weekday friday{5}; // uses overload (2) static_assert(friday == std::chrono::Friday ); for (int y{2020}; y <= 2024; ++y) { const std::chrono::year cur_year{y}; for (int cur_month{1}; cur_month != 13; ++cur_month) { const std::chrono::year_month_day ymd{cur_year/cur_month/13}; const std::chrono::weekday cur_weekday{std::chrono::sys_days (ymd)}; // (3) if (cur_weekday == friday) std::cout << ymd << " is " << friday << '\n'; } } }
Output:
2020年03月13日 is Fri 2020年11月13日 is Fri 2021年08月13日 is Fri 2022年05月13日 is Fri 2023年01月13日 is Fri 2023年10月13日 is Fri 2024年09月13日 is Fri 2024年12月13日 is Fri