29 Time library [time]

29.8 The civil calendar [time.cal]

29.8.13 Class year_month [time.cal.ym]

29.8.13.3 Non-member functions [time.cal.ym.nonmembers]

constexpr bool operator==(const year_month& x, const year_month& y) noexcept;

Returns: x.year() == y.year() && x.month() == y.month().

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constexpr strong_ordering operator<=>(const year_month& x, const year_month& y) noexcept;

Effects: Equivalent to: if (auto c = x.year() <=> y.year(); c != 0) return c; return x.month() <=> y.month();

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constexpr year_month operator+(const year_month& ym, const months& dm) noexcept;

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]).

Returns: A year_month value z such that z.ok() && z - ym == dm is true.

Complexity:

O (1)

with respect to the value of dm.

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constexpr year_month operator+(const months& dm, const year_month& ym) noexcept;

Returns: ym + dm.

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constexpr year_month operator-(const year_month& ym, const months& dm) noexcept;

Returns: ym + -dm.

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constexpr months operator-(const year_month& x, const year_month& y) noexcept;

Returns: x.year() - y.year() + months{static_cast<int>(unsigned{x.month()}) - static_cast<int>(unsigned{y.month()})}

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constexpr year_month operator+(const year_month& ym, const years& dy) noexcept;

Returns: (ym.year() + dy) / ym.month().

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constexpr year_month operator+(const years& dy, const year_month& ym) noexcept;

Returns: ym + dy.

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constexpr year_month operator-(const year_month& ym, const years& dy) noexcept;

Returns: ym + -dy.

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template<class charT, class traits>
  basic_ostream<charT, traits>&
    operator<<(basic_ostream<charT, traits>& os, const year_month& ym);

Effects: Equivalent to: return os << format(os.getloc(), STATICALLY-WIDEN<charT>("{}/{:L}"), ym.year(), ym.month());

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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& ym, basic_string<charT, traits, Alloc>* abbrev = nullptr,
                minutes* offset = nullptr);

Effects: Attempts to parse the input stream is into the year_month ym using the format flags given in the NTCTS fmt as specified in [time.parse].

If the parse fails to decode a valid year_month, is.setstate(ios_base::failbit) is called and ym is not 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.