[time.cal.wd.nonmembers] (original) (raw)

30 Time library [time]

30.8 The civil calendar [time.cal]

30.8.6 Class weekday [time.cal.wd]

30.8.6.3 Non-member functions [time.cal.wd.nonmembers]

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

constexpr weekday operator+(const weekday& x, const days& y) noexcept;

Returns: weekday{modulo(static_cast<long long>(x.wd_) + y.count(), 7)} where modulo(n, 7) computes the remainder of n divided by 7 using Euclidean division.

[Note 1:

Given a divisor of 7, Euclidean division truncates towards negative infinity and always produces a remainder in the range of [0, 6].

Assuming no overflow in the signed summation, this operation results in a weekday holding a value in the range [0, 6] even if !x.ok().

— _end note_]

[Example 1:

Monday + days{6} == Sunday.

— _end example_]

constexpr weekday operator+(const days& x, const weekday& y) noexcept;

constexpr weekday operator-(const weekday& x, const days& y) noexcept;

constexpr days operator-(const weekday& x, const weekday& y) noexcept;

Returns: If x.ok() == trueand y.ok() == true, returns a value din the range [days{0}, days{6}] satisfying y + d == x.

Otherwise the value returned is unspecified.

[Example 2:

Sunday - Monday == days{6}.

— _end example_]

template<class charT, class traits> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const weekday& wd);

Effects: Equivalent to:return os << (wd.ok() ? format(os.getloc(), _STATICALLY-WIDEN_<charT>("{:L%a}"), wd) : format(os.getloc(), STATICALLY-WIDEN<charT>("{} is not a valid weekday"),static_cast<unsigned>(wd.wd_)));

template<class charT, class traits, class Alloc = allocator<charT>> basic_istream<charT, traits>& from_stream(basic_istream<charT, traits>& is, const charT* fmt, weekday& wd, basic_string<charT, traits, Alloc>* abbrev = nullptr, minutes* offset = nullptr);

Effects: Attempts to parse the input stream isinto the weekday wd using the format flags given in the NTCTS fmtas specified in [time.parse].

If the parse fails to decode a valid weekday,is.setstate(ios_base​::​failbit) is called andwd 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.