std::chrono::year_month_day_last

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

constructs a year_month_day_last object
(public member function)
modifies the time point by some number of months or years
(public member function)
accesses the fields of this object
(public member function)
converts to a std::chrono::time_point
(public member function)
checks whether this object represents a valid date
(public member function)

Nonmember functions

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

Helper classes

(C++20)
 formatting support for year_month_day_last
(class template specialization)
(C++26)
 hash support for std::chrono::year_month_day_last
(class template specialization)

Example

#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

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

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