27 Time library [time]

27.8 The civil calendar [time.cal]

27.8.9 Class month_­day [time.cal.md]

27.8.9.3 Non-member functions [time.cal.md.nonmembers]

constexpr bool operator==(const month_day& x, const month_day& y) noexcept;
Returns: x.month() == y.month() && x.day() == y.day().
constexpr strong_ordering operator<=>(const month_day& x, const month_day& y) noexcept;
Effects: Equivalent to:
if (auto c = x.month() <=> y.month(); c != 0) return c;
return x.day() <=> y.day();
template<class charT, class traits> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const month_day& md);
Effects: Equivalent to:
return os << format(os.getloc(), STATICALLY-WIDEN<charT>("{}/{}"),
                    md.month(), md.day());
template<class charT, class traits, class Alloc = allocator<charT>> basic_istream<charT, traits>& from_stream(basic_istream<charT, traits>& is, const charT* fmt, month_day& md, basic_string<charT, traits, Alloc>* abbrev = nullptr, minutes* offset = nullptr);
Effects: Attempts to parse the input stream is into the month_­day md using the format flags given in the NTCTS fmt as specified in [time.parse].
If the parse fails to decode a valid month_­day, is.setstate(ios_­base​::​failbit) shall be called and md 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.