# std::chrono::year_month_day_last

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< cpp‎ | chrono

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+=operator-= | modifies the time point by some number of months or years (public member function)
yearmonthdaymonth_day_last | accesses the fields of this object (public member function)
operator sys_daysoperator local_days | converts to a std::chrono::time_point (public member function)
ok | checks whether this object represents a valid date (public member function)

### Nonmember functions

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

### Helper classes

std::formatter<std::chrono::year_month_day_last> (C++20) | formatting support for `year_month_day_last` (class template specialization)
std::hash<std::chrono::year_month_day_last> (C++26) | hash support for `std::chrono::year_month_day_last` (class template specialization)

### Example

Run this code

    #include <chrono>
    #include <iostream>

    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 last day of present month (" << ymdl << ") is: "
                  << std::chrono::year_month_day{ymdl}.day() << '\n';

        // The 'last' object can be placed 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 && ymdl2 == ymdl3);
    }

Possible output:

    The last day of present month (2023/Aug/last) is: 31

### See also

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

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