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std::chrono::operator/ (calendar)

Defined in header <chrono>
year_month
constexpr auto operator/( const std::chrono::year& y,
                          const std::chrono::month& m ) noexcept
    -> std::chrono::year_month;
(1) (since C++20)
constexpr auto operator/( const std::chrono::year& y, int m ) noexcept
    -> std::chrono::year_month;
(2) (since C++20)
month_day
constexpr auto operator/( const std::chrono::month& m,
                          const std::chrono::day& d ) noexcept
    -> std::chrono::month_day;
(3) (since C++20)
constexpr auto operator/( const std::chrono::month& m, int d ) noexcept
    -> std::chrono::month_day;
(4) (since C++20)
constexpr auto operator/( int m, const std::chrono::day& d ) noexcept
    -> std::chrono::month_day;
(5) (since C++20)
constexpr auto operator/( const std::chrono::day& d,
                          const std::chrono::month& m ) noexcept
   -> std::chrono::month_day;
(6) (since C++20)
constexpr auto operator/( const std::chrono::day& d, int m ) noexcept
    -> std::chrono::month_day;
(7) (since C++20)
month_day_last
constexpr auto operator/( const std::chrono::month& m,
                         std::chrono::last_spec ) noexcept
    -> std::chrono::month_day_last;
(8) (since C++20)
constexpr auto operator/( int m, std::chrono::last_spec ) noexcept
    -> std::chrono::month_day_last;
(9) (since C++20)
constexpr auto operator/( std::chrono::last_spec,
                          const std::chrono::month& m ) noexcept
    -> std::chrono::month_day_last;
(10) (since C++20)
constexpr auto operator/( std::chrono::last_spec, int m ) noexcept
    -> std::chrono::month_day_last;
(11) (since C++20)
month_weekday
constexpr auto operator/( const std::chrono::month& m,
                          const std::chrono::weekday_indexed& wdi ) noexcept 
    -> std::chrono::month_weekday;
(12) (since C++20)
constexpr auto operator/( int m, const std::chrono::weekday_indexed& wdi ) noexcept
    -> std::chrono::month_weekday;
(13) (since C++20)
constexpr auto operator/( const std::chrono::weekday_indexed& wdi,
                          const std::chrono::month& m ) noexcept
    -> std::chrono::month_weekday;
(14) (since C++20)
constexpr auto operator/( const std::chrono::weekday_indexed& wdi, int m ) noexcept
    -> std::chrono::month_weekday;
(15) (since C++20)
month_weekday_last
constexpr auto operator/( const std::chrono::month& m,
                          const std::chrono::weekday_last& wdl ) noexcept
    -> std::chrono::month_weekday_last;
(16) (since C++20)
constexpr auto operator/( int m, const std::chrono::weekday_last& wdl ) noexcept
    -> std::chrono::month_weekday_last;
(17) (since C++20)
constexpr auto operator/( const std::chrono::weekday_last& wdl,
                          const std::chrono::month& m ) noexcept
    -> std::chrono::month_weekday_last;
(18) (since C++20)
constexpr auto operator/( const std::chrono::weekday_last& wdl, int m ) noexcept
    -> std::chrono::month_weekday_last;
(19) (since C++20)
year_month_day
constexpr auto operator/( const std::chrono::year_month& ym,
                          const std::chrono::day& d ) noexcept
    -> std::chrono::year_month_day;
(20) (since C++20)
constexpr auto operator/( const std::chrono::year_month& ym, int d ) noexcept
    -> std::chrono::year_month_day;
(21) (since C++20)
constexpr auto operator/( const std::chrono::year& y,
                          const std::chrono::month_day& md ) noexcept
    -> std::chrono::year_month_day;
(22) (since C++20)
constexpr auto operator/( int y, const std::chrono::month_day& md ) noexcept
    -> std::chrono::year_month_day;
(23) (since C++20)
constexpr auto operator/( const std::chrono::month_day& md,
                          const std::chrono::year& y ) noexcept
    -> std::chrono::year_month_day;
(24) (since C++20)
constexpr auto operator/( const std::chrono::month_day& md, int y ) noexcept
    -> std::chrono::year_month_day;
(25) (since C++20)
year_month_day_last
constexpr auto operator/( const std::chrono::year_month& ym,
                         std::chrono::last_spec ) noexcept
    -> std::chrono::year_month_day_last;
(26) (since C++20)
constexpr auto operator/( const std::chrono::year& y,
                          const std::chrono::month_day_last& mdl ) noexcept
    -> std::chrono::year_month_day_last;
(27) (since C++20)
constexpr auto operator/( int y, const std::chrono::month_day_last& mdl ) noexcept
    -> std::chrono::year_month_day_last;
(28) (since C++20)
constexpr auto operator/( const std::chrono::month_day_last& mdl,
                          const std::chrono::year& y ) noexcept
    -> std::chrono::year_month_day_last;
(29) (since C++20)
constexpr auto operator/( const std::chrono::month_day_last& mdl, int y ) noexcept
    -> std::chrono::year_month_day_last;
(30) (since C++20)
year_month_weekday
constexpr auto operator/( const std::chrono::year_month& ym,
                          const std::chrono::weekday_indexed& wdi ) noexcept
    -> std::chrono::year_month_weekday;
(31) (since C++20)
constexpr auto operator/( const std::chrono::year& y,
                          const std::chrono::month_weekday& mwd ) noexcept
    -> std::chrono::year_month_weekday;
(32) (since C++20)
constexpr auto operator/( int y, const std::chrono::month_weekday& mwd ) noexcept
    -> std::chrono::year_month_weekday;
(33) (since C++20)
constexpr auto operator/( const std::chrono::month_weekday& mwd,
                          const std::chrono::year& y ) noexcept
    -> std::chrono::year_month_weekday;
(34) (since C++20)
constexpr auto operator/( const std::chrono::month_weekday& mwd, int y ) noexcept
    -> std::chrono::year_month_weekday;
(35) (since C++20)
year_month_weekday_last
constexpr auto operator/( const std::chrono::year_month& ym,
                          const std::chrono::weekday_last& wdl ) noexcept
    -> std::chrono::year_month_weekday_last;
(36) (since C++20)
constexpr auto operator/( const std::chrono::year& y,
                          const std::chrono::month_weekday_last& mwdl ) noexcept
    -> std::chrono::year_month_weekday_last;
(37) (since C++20)
constexpr auto operator/( int y, const std::chrono::month_weekday_last& mwdl ) noexcept
    -> std::chrono::year_month_weekday_last;
(38) (since C++20)
constexpr auto operator/( const std::chrono::month_weekday_last& mwdl,
                          const std::chrono::year& y ) noexcept
    -> std::chrono::year_month_weekday_last;
(39) (since C++20)
constexpr auto operator/( const std::chrono::month_weekday_last& mwdl, int y ) noexcept
    -> std::chrono::year_month_weekday_last;
(40) (since C++20)

These operator/ overloads provide a conventional syntax for the creation of Gregorian calendar dates.

For creation of a full date, any of the following three orders are accepted:

  • year/month/day
  • month/day/year
  • day/month/year.

In each case day can replaced with one of:

  • std::chrono::last, for the last day of the month;
  • weekday[i], for the i-th weekday of the month;
  • weekday[std::chrono::last], for the last weekday of the month.

A plain integer is accepted if its meaning is unambiguous from the types of other operands: 2005y/4/5 is allowed, but 5/April/2005 is not.

Partial-date types (year_month, month_day, etc.) can be created by not applying the second operator/ in any of the three orders.

Return value

20) std::chrono::year_month_day(ym.year(), ym.month(), d)
21) std::chrono::year_month_day(ym.year(), ym.month(), std::chrono::day(d))
22,24) std::chrono::year_month_day(y, md.month(), md.day())
23,25) std::chrono::year_month_day(std::chrono::year(y), md.month(), md.day())
31) std::chrono::year_month_weekday(ym.year(), ym.month(), wdi)
32,34) std::chrono::year_month_weekday(y, mwd.month(), mwd.weekday_indexed())
33,35) std::chrono::year_month_weekday(std::chrono::year(y), mwd.month(), mwd.weekday_indexed())
36) std::chrono::year_month_weekday_last(ym.year(), ym.month(), wdl)
37,39) std::chrono::year_month_weekday_last(y, mwdl.month(), mwdl.weekday_last())
38,40) std::chrono::year_month_weekday_last(std::chrono::year(y), mwdl.month(), mwdl.weekday_last())

Example

#include <iostream>
#include <chrono>
using namespace std::chrono;
 
int main()
{
    std::cout << std::boolalpha;
 
    constexpr auto ym {2021y/8};
    std::cout << (ym == year_month(year(2021), August)) << ' ';
 
    constexpr auto md {9/15d};
    std::cout << (md == month_day(September, day(15))) << ' ';
 
    constexpr auto mdl {October/last};
    std::cout << (mdl == month_day_last(month(10))) << ' ';
 
    constexpr auto mw {11/Monday[3]};
    std::cout << (mw == month_weekday(November, Monday[3])) << ' ';
 
    constexpr auto mwdl {December/Sunday[last]};
    std::cout << (mwdl == month_weekday_last(month(12), weekday_last(Sunday))) << ' ';
 
    // Those three year/month/day orders that people actually use on this planet:
    constexpr auto ymd {year(2021)/January/day(23)};
    static_assert(ymd == month{1}/23/2021);
    static_assert(ymd == day{23}/1/2021);
    std::cout << (ymd == year_month_day(2021y, month(January), 23d)) << '\n';
}

Output:

true true true true true true

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