27 Time library [time]

27.8 The civil calendar [time.cal]

27.8.15 Class year_­month_­day_­last [time.cal.ymdlast]

27.8.15.1 Overview [time.cal.ymdlast.overview]

namespace std::chrono {
  class year_month_day_last {
    chrono::year           y_;          // exposition only
    chrono::month_day_last mdl_;        // exposition only

  public:
    constexpr year_month_day_last(const chrono::year& y,
                                  const chrono::month_day_last& mdl) noexcept;

    constexpr year_month_day_last& operator+=(const months& m) noexcept;
    constexpr year_month_day_last& operator-=(const months& m) noexcept;
    constexpr year_month_day_last& operator+=(const years& y)  noexcept;
    constexpr year_month_day_last& operator-=(const years& y)  noexcept;

    constexpr chrono::year           year()           const noexcept;
    constexpr chrono::month          month()          const noexcept;
    constexpr chrono::month_day_last month_day_last() const noexcept;
    constexpr chrono::day            day()            const noexcept;

    constexpr          operator sys_days()   const noexcept;
    constexpr explicit operator local_days() const noexcept;
    constexpr bool ok() const noexcept;
  };
}
1
#
year_­month_­day_­last represents the last day of a specific year and month.
year_­month_­day_­last is a field-based time point with a resolution of days, except that it is restricted to pointing to the last day of a year and month.
[ Note
:
year_­month_­day_­last supports years- and months-oriented arithmetic, but not days-oriented arithmetic.
For the latter, there is a conversion to sys_­days, which efficiently supports days-oriented arithmetic.
— end note
 ]
year_­month_­day_­last meets the Cpp17EqualityComparable (Table 25) and Cpp17LessThanComparable (Table 26) requirements.
2
#
year_­month_­day_­last is a trivially copyable and standard-layout class type.

27.8.15.2 Member functions [time.cal.ymdlast.members]

🔗
constexpr year_month_day_last(const chrono::year& y, const chrono::month_day_last& mdl) noexcept;
1
#
Effects: Initializes y_­ with y and mdl_­ with mdl.
🔗
constexpr year_month_day_last& operator+=(const months& m) noexcept;
2
#
Constraints: If the argument supplied by the caller for the months parameter is convertible to years, its implicit conversion sequence to years is worse than its implicit conversion sequence to months ([over.ics.rank]).
3
#
Effects: *this = *this + m.
4
#
Returns: *this.
🔗
constexpr year_month_day_last& operator-=(const months& m) noexcept;
5
#
Constraints: If the argument supplied by the caller for the months parameter is convertible to years, its implicit conversion sequence to years is worse than its implicit conversion sequence to months ([over.ics.rank]).
6
#
Effects: *this = *this - m.
7
#
Returns: *this.
🔗
constexpr year_month_day_last& operator+=(const years& y) noexcept;
8
#
Effects: *this = *this + y.
9
#
Returns: *this.
🔗
constexpr year_month_day_last& operator-=(const years& y) noexcept;
10
#
Effects: *this = *this - y.
11
#
Returns: *this.
🔗
constexpr chrono::year year() const noexcept;
12
#
Returns: y_­.
🔗
constexpr chrono::month month() const noexcept;
13
#
Returns: mdl_­.month().
🔗
constexpr chrono::month_day_last month_day_last() const noexcept;
14
#
Returns: mdl_­.
🔗
constexpr chrono::day day() const noexcept;
15
#
Returns: If ok() is true, returns a day representing the last day of the (year, month) pair represented by *this.
Otherwise, the returned value is unspecified.
16
#
[ Note
:
This value may be computed on demand.
— end note
 ]
🔗
constexpr operator sys_days() const noexcept;
17
#
Returns: sys_­days{year()/month()/day()}.
🔗
constexpr explicit operator local_days() const noexcept;
18
#
Returns: local_­days{sys_­days{*this}.time_­since_­epoch()}.
🔗
constexpr bool ok() const noexcept;
19
#
Returns: y_­.ok() && mdl_­.ok().

27.8.15.3 Non-member functions [time.cal.ymdlast.nonmembers]

🔗
constexpr bool operator==(const year_month_day_last& x, const year_month_day_last& y) noexcept;
1
#
Returns: x.year() == y.year() && x.month_­day_­last() == y.month_­day_­last().
🔗
constexpr strong_ordering operator<=>(const year_month_day_last& x, const year_month_day_last& y) noexcept;
2
#
Effects: Equivalent to: 
if (auto c = x.year() <=> y.year(); c != 0) return c;
return x.month_day_last() <=> y.month_day_last();
🔗
constexpr year_month_day_last operator+(const year_month_day_last& ymdl, const months& dm) noexcept;
3
#
Constraints: If the argument supplied by the caller for the months parameter is convertible to years, its implicit conversion sequence to years is worse than its implicit conversion sequence to months ([over.ics.rank]).
4
#
Returns: (ymdl.year() / ymdl.month() + dm) / last.
🔗
constexpr year_month_day_last operator+(const months& dm, const year_month_day_last& ymdl) noexcept;
5
#
Constraints: If the argument supplied by the caller for the months parameter is convertible to years, its implicit conversion sequence to years is worse than its implicit conversion sequence to months ([over.ics.rank]).
6
#
Returns: ymdl + dm.
🔗
constexpr year_month_day_last operator-(const year_month_day_last& ymdl, const months& dm) noexcept;
7
#
Constraints: If the argument supplied by the caller for the months parameter is convertible to years, its implicit conversion sequence to years is worse than its implicit conversion sequence to months ([over.ics.rank]).
8
#
Returns: ymdl + (-dm).
🔗
constexpr year_month_day_last operator+(const year_month_day_last& ymdl, const years& dy) noexcept;
9
#
Returns: {ymdl.year()+dy, ymdl.month_­day_­last()}.
🔗
constexpr year_month_day_last operator+(const years& dy, const year_month_day_last& ymdl) noexcept;
10
#
Returns: ymdl + dy.
🔗
constexpr year_month_day_last operator-(const year_month_day_last& ymdl, const years& dy) noexcept;
11
#
Returns: ymdl + (-dy).
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template<class charT, class traits> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const year_month_day_last& ymdl);
12
#
Effects: Equivalent to: 
return os << format(os.getloc(), STATICALLY-WIDEN<charT>("{}/{}"),
                    ymdl.year(), ymdl.month_day_last());