25 Time library [time]

25.8 The civil calendar [time.cal]

25.8.14 Class year_­month_­day [time.cal.ymd]

25.8.14.3 Non-member functions [time.cal.ymd.nonmembers]

constexpr bool operator==(const year_month_day& x, const year_month_day& y) noexcept;
Returns: x.year() == y.year() && x.month() == y.month() && x.day() == y.day().
constexpr bool operator<(const year_month_day& x, const year_month_day& y) noexcept;
Returns: If x.year() < y.year(), returns true.
Otherwise, if x.year() > y.year(), returns false.
Otherwise, if x.month() < y.month(), returns true.
Otherwise, if x.month() > y.month(), returns false.
Otherwise, returns x.day() < y.day().
constexpr year_month_day operator+(const year_month_day& ymd, const months& dm) noexcept;
Returns: (ymd.year() / ymd.month() + dm) / ymd.day().
[Note
:
If ymd.day() is in the range [1d, 28d], ok() will return true for the resultant year_­month_­day.
end note
]
constexpr year_month_day operator+(const months& dm, const year_month_day& ymd) noexcept;
Returns: ymd + dm.
constexpr year_month_day operator-(const year_month_day& ymd, const months& dm) noexcept;
Returns: ymd + (-dm).
constexpr year_month_day operator+(const year_month_day& ymd, const years& dy) noexcept;
Returns: (ymd.year() + dy) / ymd.month() / ymd.day().
[Note
:
If ymd.month() is February and ymd.day() is not in the range [1d, 28d], ok() may return false for the resultant year_­month_­day.
end note
]
constexpr year_month_day operator+(const years& dy, const year_month_day& ymd) noexcept;
Returns: ymd + dy.
constexpr year_month_day operator-(const year_month_day& ymd, const years& dy) noexcept;
Returns: ymd + (-dy).
template<class charT, class traits> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const year_month_day& ymd);
Effects: Inserts format(fmt, ymd) where fmt is "%F" widened to charT.
If !ymd.ok(), appends with " is not a valid date".
Returns: os.
template<class charT, class traits> basic_ostream<charT, traits>& to_stream(basic_ostream<charT, traits>& os, const charT* fmt, const year_month_day& ymd);
Effects: Streams ymd into os using the format specified by the NTCTS fmt.
fmt encoding follows the rules specified in [time.format].
Returns: os.
template<class charT, class traits, class Alloc = allocator<charT>> basic_istream<charT, traits>& from_stream(basic_istream<charT, traits>& is, const charT* fmt, year_month_day& ymd, basic_string<charT, traits, Alloc>* abbrev = nullptr, minutes* offset = nullptr);
Effects: Attempts to parse the input stream is into the year_­month_­day ymd using the format flags given in the NTCTS fmt as specified in [time.parse].
If the parse fails to decode a valid year_­month_­day, is.setstate(ios_­base::failbit) shall be called and ymd shall not be modified.
If %Z is used and successfully parsed, that value will be assigned to *abbrev if abbrev is non-null.
If %z (or a modified variant) is used and successfully parsed, that value will be assigned to *offset if offset is non-null.
Returns: is.