std::ranges::view_interface<D>::back
From cppreference.com
< cpp | ranges | view interface
|
constexpr decltype(
auto
) back(
)
requires ranges::bidirectional_range <D> && ranges::common_range <D> ; |
(1) | (since C++20) |
|
constexpr decltype(
auto
) back(
)
const
requires ranges::bidirectional_range < const D> && ranges::common_range < const D> ; |
(2) | (since C++20) |
The default implementation of back() member function returns the last element in the view of the derived type. Whether the element is returned by value or by reference depends on the operator*
1) Let
derived be
static_cast
<D&
>
(
*this)
. Equivalent to
return
*
ranges::prev
(
ranges::end
(derived)
)
;
. The behavior is undefined if empty() is true
2) Same as (1), except that
derived is
static_cast
<
const D&
>
(
*this)
Parameters
(none)
Return value
The last element in the view.
Notes
In C++20, no type derived from std::ranges::view_interface in the standard library provides their own back() member function.
However, following derived types cannot use the default implementations, as they never satisfy neither bidirectional_range nor common_range
- std::ranges::basic_istream_view
- std::ranges::lazy_split_view
- std::ranges::split_view
- std::ranges::take_while_view
The inherited back() member function is available for std::ranges::empty_view, but a call to it always results in undefined behavior.
Example
| This section is incomplete Reason: no example |
See also
|
(C++14)
|
returns a reverse iterator to the beginning of a container or array (function template) |
|
(C++20)
|
returns a reverse iterator to a range (customization point object) |
|
(C++20)
|
returns a reverse iterator to a read-only range (customization point object) |