NAME¶

std::chrono::year_month_day_last - std::chrono::year_month_day_last

Synopsis¶

Defined in header <chrono>
class year_month_day_last; (since C++20)

The class year_month_day_last represents the last day of a specific year and month.
It is a field-based time point, with a resolution of std::chrono::days, subject to
the limit that it can only represent the last day of a month.

std::chrono::years- and std::chrono::months-oriented arithmetic are supported
directly. An implicit conversion to std::chrono::sys_days allows
std::chrono::days-oriented arithmetic to be performed efficiently.

year_month_day_last is a TriviallyCopyable StandardLayoutType.

Member functions¶

constructor constructs a year_month_day_last object
(public member function)
operator+= modifies the time point by some number of months or years
operator-= (public member function)
year
month accesses the fields of this object
day (public member function)
month_day_last
operator sys_days converts to a std::chrono::time_point
operator local_days (public member function)
ok checks whether this object represents a valid date
(public member function)

Nonmember functions

operator== compares two year_month_day_last values
operator<=> (function)
(C++20)
operator+ adds or subtracts a year_month_day_last and some number of years or
operator- months
(C++20) (function)
operator<< outputs a year_month_day_last into a stream
(C++20) (function template)

Helper classes¶

specialization of std::formatter
std::formatter<std::chrono::year_month_day_last> that formats a year_month_day_last
(C++20) according to the provided format
(class template specialization)

Example¶

// Run this code

#include <iostream>
#include <chrono>

// until online compiler supports streaming the year_month_day_last:
std::ostream& operator<< (std::ostream& os, std::chrono::year_month_day_last ymdl) {
return os << static_cast<int>(ymdl.year()) << '/'
<< static_cast<unsigned>(ymdl.month()) << '/'
<< static_cast<unsigned>(ymdl.day());
}

int main()
{
const auto ymd = std::chrono::year_month_day{
std::chrono::floor<std::chrono::days>(
std::chrono::system_clock::now()
)
};

const std::chrono::year_month_day_last ymdl{
ymd.year(), ymd.month() / std::chrono::last
};
std::cout << "The date of the last day of this month is: " << ymdl << '\n';

// The `last` object can be places wherever it is legal to place a `day`:
using namespace std::chrono;
constexpr std::chrono::year_month_day_last
ymdl1 = 2023y / February / last,
ymdl2 = last / February / 2023y,
ymdl3 = February / last / 2023y;
static_assert( ymdl1 == ymdl2 and ymdl2 == ymdl3 );
}

Possible output:¶

The date of the last day of this month is: 2021/11/30

See also¶

year_month_day represents a specific year, month, and day
(C++20) (class)