30 Time library [time]

30.11 Time zones [time.zone]

30.11.2 Time zone database [time.zone.db]

30.11.2.2 Class tzdb_list [time.zone.db.list]

namespace std::chrono { class tzdb_list { public: tzdb_list(const tzdb_list&) = delete; tzdb_list& operator=(const tzdb_list&) = delete; // unspecified additional constructors class const_iterator; const tzdb& front() const noexcept; const_iterator erase_after(const_iterator p); const_iterator begin() const noexcept; const_iterator end() const noexcept; const_iterator cbegin() const noexcept; const_iterator cend() const noexcept; }; }
The tzdb_list database is a singleton; the unique object of type tzdb_list can be accessed via the get_tzdb_list() function.
[Note 1: 
This access is only needed for those applications that need to have long uptimes and have a need to update the time zone database while running.
Other applications can implicitly access the front() of this list via the read-only namespace scope functions get_tzdb(), locate_zone(), and current_zone().
— end note]
The tzdb_list object contains a list of tzdb objects.
tzdb_list​::​const_iterator is a constant iterator which meets the Cpp17ForwardIterator requirements and has a value type of tzdb.
const tzdb& front() const noexcept;
Synchronization: This operation is thread-safe with respect to reload_tzdb().
[Note 2: 
reload_tzdb() pushes a new tzdb onto the front of this container.
— end note]
Returns: A reference to the first tzdb in the container.
const_iterator erase_after(const_iterator p);
Preconditions: The iterator following p is dereferenceable.
Effects: Erases the tzdb referred to by the iterator following p.
Postconditions: No pointers, references, or iterators are invalidated except those referring to the erased tzdb.
[Note 3: 
It is not possible to erase the tzdb referred to by begin().
— end note]
Returns: An iterator pointing to the element following the one that was erased, or end() if no such element exists.
Throws: Nothing.
const_iterator begin() const noexcept;
Returns: An iterator referring to the first tzdb in the container.
const_iterator end() const noexcept;
Returns: An iterator referring to the position one past the last tzdb in the container.
const_iterator cbegin() const noexcept;
Returns: begin().
const_iterator cend() const noexcept;
Returns: end().