std::chrono::year_month_day::year_month_day(3)

NAME
std::chrono::year_month_day::year_month_day - std::chrono::year_month_day::year_month_day

Synopsis
   year_month_day() = default; (1) (since C++20)
   constexpr year_month_day( const std::chrono::year& y,
                        const std::chrono::month& m, (2) (since C++20)
                        const std::chrono::day& d ) noexcept;
   constexpr year_month_day( const std::chrono::year_month_day_last& (3) (since C++20)
   ymdl ) noexcept;
   constexpr year_month_day( const std::chrono::sys_days& dp ) (4) (since C++20)
   noexcept;
   constexpr explicit year_month_day( const std::chrono::local_days& (5) (since C++20)
   dp ) noexcept;
   Constructs a year_month_day object.
   1) Default constructor leaves the date uninitialized.
   2) Constructs a year_month_day object that stores the year y, month m and day d.
   3) Constructs a year_month_day object that stores the year ymdl.year(), month
   ymdl.month() and day ymdl.day().
   4) Constructs a year_month_day object that represent the same date as the one
   represented by dp.
   5) Constructs a year_month_day object that represent the same date as the one
   represented by dp, as if by year_month_day(sys_days(dp.time_since_epoch())).
   Constructors (3,4) define implicit conversions from std::chrono::year_month_day_last
   and std::chrono::sys_days, respectively.
   For any year_month_day object ymd representing a valid date (ymd.ok() == true),
   converting ymd to sys_days and back yields the same value.

Notes
   A year_month_day can also be created by combining one of the partial-date types
   std::chrono::year_month and std::chrono::month_day with the missing component (day
   and year, respectively) using operator/.

Example
// Run this code
 #include <chrono>
 #include <iostream>
 int main()
 {
     using namespace std::chrono;
     constexpr auto ymd2 = std::chrono::year_month_day(
         2020y, std::chrono::January, 31d // overload (2)
     );
     std::cout << "ymd2: " << ymd2 << '\n';
     constexpr auto ymd3 = std::chrono::year_month_day(
         std::chrono::April / std::chrono::Monday[last] / 2023y // overload (3)
     );
     std::cout << "ymd3: " << ymd3 << '\n';
     const auto now = std::chrono::system_clock::now();
     const auto ymd4 = std::chrono::year_month_day(
         std::chrono::floor<std::chrono::days>(now) // overload (4)
     );
     std::cout << "ymd4: " << ymd4 << '\n';
 }

Possible output:
 ymd2: 2020-01-31
 ymd3: 2023-04-24
 ymd4: 2023-08-30

See also
   operator/ conventional syntax for Gregorian calendar date creation
   (C++20) (function)