std::chrono::month_day::month_day(3)

NAME
std::chrono::month_day::month_day - std::chrono::month_day::month_day

Synopsis
   month_day() = default; (1) (since C++20)
   constexpr month_day( const std::chrono::month& m, (2) (since C++20)
                        const std::chrono::day& d ) noexcept;
   Constructs a month_day.
   1) Default constructor leaves the stored month and day values uninitialized.
   2) Constructs a month_day that stores the month m and the day d.

Notes
   A more convenient way to construct a month_day is with operator/, e.g.,
   std::chrono::April/1.

Example
// Run this code
 #include <chrono>
 #include <iostream>
 int main()
 {
     using namespace std::chrono_literals;
     constexpr auto mo_da = std::chrono::month_day(std::chrono::February, 29d);
     std::cout << static_cast<unsigned>(mo_da.day()) << '/'
               << static_cast<unsigned>(mo_da.month()) << '\n';
 }

Output:
 29/2

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