30 Time library [time]

30.11 Time zones [time.zone]

30.11.7 Class template zoned_time [time.zone.zonedtime]

30.11.7.1 Overview [time.zone.zonedtime.overview]

namespace std::chrono { template<class Duration, class TimeZonePtr = const time_zone*> class zoned_time { public: using duration = common_type_t<Duration, seconds>; private: TimeZonePtr zone_; // exposition only sys_time<duration> tp_; // exposition only using traits = zoned_traits<TimeZonePtr>; // exposition only public: zoned_time(); zoned_time(const zoned_time&) = default; zoned_time& operator=(const zoned_time&) = default; zoned_time(const sys_time<Duration>& st); explicit zoned_time(TimeZonePtr z); explicit zoned_time(string_view name); template<class Duration2> zoned_time(const zoned_time<Duration2, TimeZonePtr>& y); zoned_time(TimeZonePtr z, const sys_time<Duration>& st); zoned_time(string_view name, const sys_time<Duration>& st); zoned_time(TimeZonePtr z, const local_time<Duration>& tp); zoned_time(string_view name, const local_time<Duration>& tp); zoned_time(TimeZonePtr z, const local_time<Duration>& tp, choose c); zoned_time(string_view name, const local_time<Duration>& tp, choose c); template<class Duration2, class TimeZonePtr2> zoned_time(TimeZonePtr z, const zoned_time<Duration2, TimeZonePtr2>& y); template<class Duration2, class TimeZonePtr2> zoned_time(TimeZonePtr z, const zoned_time<Duration2, TimeZonePtr2>& y, choose); template<class Duration2, class TimeZonePtr2> zoned_time(string_view name, const zoned_time<Duration2, TimeZonePtr2>& y); template<class Duration2, class TimeZonePtr2> zoned_time(string_view name, const zoned_time<Duration2, TimeZonePtr2>& y, choose c); zoned_time& operator=(const sys_time<Duration>& st); zoned_time& operator=(const local_time<Duration>& lt); operator sys_time<duration>() const; explicit operator local_time<duration>() const; TimeZonePtr get_time_zone() const; local_time<duration> get_local_time() const; sys_time<duration> get_sys_time() const; sys_info get_info() const; }; zoned_time() -> zoned_time<seconds>; template<class Duration> zoned_time(sys_time<Duration>) -> zoned_time<common_type_t<Duration, seconds>>; template<class TimeZonePtrOrName> using time-zone-representation = // exposition only conditional_t<is_convertible_v<TimeZonePtrOrName, string_view>, const time_zone*, remove_cvref_t<TimeZonePtrOrName>>; template<class TimeZonePtrOrName> zoned_time(TimeZonePtrOrName&&) -> zoned_time<seconds, time-zone-representation<TimeZonePtrOrName>>; template<class TimeZonePtrOrName, class Duration> zoned_time(TimeZonePtrOrName&&, sys_time<Duration>) -> zoned_time<common_type_t<Duration, seconds>, time-zone-representation<TimeZonePtrOrName>>; template<class TimeZonePtrOrName, class Duration> zoned_time(TimeZonePtrOrName&&, local_time<Duration>, choose = choose::earliest) -> zoned_time<common_type_t<Duration, seconds>, time-zone-representation<TimeZonePtrOrName>>; template<class Duration, class TimeZonePtrOrName, class TimeZonePtr2> zoned_time(TimeZonePtrOrName&&, zoned_time<Duration, TimeZonePtr2>, choose = choose::earliest) -> zoned_time<common_type_t<Duration, seconds>, time-zone-representation<TimeZonePtrOrName>>; }

zoned_time represents a logical pairing of a time_zone and a time_point with precision Duration.

zoned_time<Duration> maintains the invariant that it always refers to a valid time zone and represents a point in time that exists and is not ambiguous in that time zone.

If Duration is not a specialization of chrono::duration, the program is ill-formed.

Every constructor of zoned_time that accepts a string_view as its first parameter does not participate in class template argument deduction ([over.match.class.deduct]).

30.11.7.2 Constructors [time.zone.zonedtime.ctor]

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zoned_time();

Constraints: traits::default_zone() is a well-formed expression.

Effects: Initializes zone_ with traits::default_zone() and default constructs tp_.

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zoned_time(const sys_time<Duration>& st);

Constraints: traits::default_zone() is a well-formed expression.

Effects: Initializes zone_ with traits::default_zone() and tp_ with st.

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explicit zoned_time(TimeZonePtr z);

Preconditions: z refers to a time zone.

Effects: Initializes zone_ with std::move(z) and default constructs tp_.

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explicit zoned_time(string_view name);

Constraints: traits::locate_zone(string_view{}) is a well-formed expression and zoned_time is constructible from the return type of traits::locate_zone(string_view{}).

Effects: Initializes zone_ with traits::locate_zone(name) and default constructs tp_.

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template<class Duration2>
  zoned_time(const zoned_time<Duration2, TimeZonePtr>& y);

Constraints: is_convertible_v<sys_time<Duration2>, sys_time<Duration>> is true.

Effects: Initializes zone_ with y.zone_ and tp_ with y.tp_.

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zoned_time(TimeZonePtr z, const sys_time<Duration>& st);

Preconditions: z refers to a time zone.

Effects: Initializes zone_ with std::move(z) and tp_ with st.

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zoned_time(string_view name, const sys_time<Duration>& st);

Constraints: zoned_time is constructible from the return type of traits::locate_zone(name) and st.

Effects: Equivalent to construction with {traits::locate_zone(name), st}.

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zoned_time(TimeZonePtr z, const local_time<Duration>& tp);

Constraints: is_convertible_v< decltype(declval<TimeZonePtr&>()->to_sys(local_time<Duration>{})), sys_time<duration>> is true.

Preconditions: z refers to a time zone.

Effects: Initializes zone_ with std::move(z) and tp_ with zone_->to_sys(tp).

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zoned_time(string_view name, const local_time<Duration>& tp);

Constraints: zoned_time is constructible from the return type of traits::locate_zone(name) and tp.

Effects: Equivalent to construction with {traits::locate_zone(name), tp}.

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zoned_time(TimeZonePtr z, const local_time<Duration>& tp, choose c);

Constraints: is_convertible_v< decltype(declval<TimeZonePtr&>()->to_sys(local_time<Duration>{}, choose::earliest)), sys_time<duration>> is true.

Preconditions: z refers to a time zone.

Effects: Initializes zone_ with std::move(z) and tp_ with zone_->to_sys(tp, c).

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zoned_time(string_view name, const local_time<Duration>& tp, choose c);

Constraints: zoned_time is constructible from the return type of traits::locate_zone(name), local_time<Duration>, and choose.

Effects: Equivalent to construction with {traits::locate_zone(name), tp, c}.

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template<class Duration2, class TimeZonePtr2>
  zoned_time(TimeZonePtr z, const zoned_time<Duration2, TimeZonePtr2>& y);

Constraints: is_convertible_v<sys_time<Duration2>, sys_time<Duration>> is true.

Preconditions: z refers to a valid time zone.

Effects: Initializes zone_ with std::move(z) and tp_ with y.tp_.

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template<class Duration2, class TimeZonePtr2>
  zoned_time(TimeZonePtr z, const zoned_time<Duration2, TimeZonePtr2>& y, choose);

Constraints: is_convertible_v<sys_time<Duration2>, sys_time<Duration>> is true.

Preconditions: z refers to a valid time zone.

Effects: Equivalent to construction with {z, y}.

[Note 1:

The choose parameter has no effect.

— end note]

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template<class Duration2, class TimeZonePtr2>
  zoned_time(string_view name, const zoned_time<Duration2, TimeZonePtr2>& y);

Constraints: zoned_time is constructible from the return type of traits::locate_zone(name) and the type zoned_time<Duration2, TimeZonePtr2>.

Effects: Equivalent to construction with {traits::locate_zone(name), y}.

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template<class Duration2, class TimeZonePtr2>
  zoned_time(string_view name, const zoned_time<Duration2, TimeZonePtr2>& y, choose c);

Constraints: zoned_time is constructible from the return type of traits::locate_zone(name), the type zoned_time<Duration2, TimeZonePtr2>, and the type choose.

Effects: Equivalent to construction with {traits::locate_zone(name), y, c}.

[Note 2:

The choose parameter has no effect.

— end note]

30.11.7.3 Member functions [time.zone.zonedtime.members]

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zoned_time& operator=(const sys_time<Duration>& st);

Effects: After assignment, get_sys_time() == st.

This assignment has no effect on the return value of get_time_zone().

Returns: *this.

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zoned_time& operator=(const local_time<Duration>& lt);

Effects: After assignment, get_local_time() == lt.

This assignment has no effect on the return value of get_time_zone().

Returns: *this.

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operator sys_time<duration>() const;

Returns: get_sys_time().

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explicit operator local_time<duration>() const;

Returns: get_local_time().

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TimeZonePtr get_time_zone() const;

Returns: zone_.

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local_time<duration> get_local_time() const;

Returns: zone_->to_local(tp_).

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sys_time<duration> get_sys_time() const;

Returns: tp_.

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sys_info get_info() const;

Returns: zone_->get_info(tp_).

30.11.7.4 Non-member functions [time.zone.zonedtime.nonmembers]

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template<class Duration1, class Duration2, class TimeZonePtr>
  bool operator==(const zoned_time<Duration1, TimeZonePtr>& x,
                  const zoned_time<Duration2, TimeZonePtr>& y);

Returns: x.zone_ == y.zone_ && x.tp_ == y.tp_.

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template<class charT, class traits, class Duration, class TimeZonePtr>
  basic_ostream<charT, traits>&
    operator<<(basic_ostream<charT, traits>& os,
               const zoned_time<Duration, TimeZonePtr>& t);

Effects: Equivalent to: return os << format(os.getloc(), STATICALLY-WIDEN<charT>("{:L%F %T %Z}"), t);