std::ranges::view_interface<D>::data
constexpr auto data()
requires std::contiguous_iterator<ranges::iterator_t<D>>; |
(1) | (since C++20) |
constexpr auto data() const
requires ranges::range<const D> &&
std::contiguous_iterator<ranges::iterator_t<const D>>; |
(2) | (since C++20) |
The default implementation of data() member function obtains the address denoted by the beginning iterator via std::to_address, which is also the lowest address of the contiguous storage (implied by contiguous_iterator) referenced by the view of the derived type when the view is not empty.
derived be
static_cast<D&>(*this). Equivalent to
return std::to_address(ranges::begin(derived));.
derived is
static_cast<const D&>(*this).
Parameters
(none).
Return value
The address denoted by the beginning iterator.
Notes
Following derived types may use the default implementation of data():
-
std::ranges::common_view -
std::ranges::drop_view -
std::ranges::drop_while_view -
std::ranges::ref_view -
std::ranges::subrange -
std::ranges::take_view -
std::ranges::take_while_view
Following types are derived from std::ranges::view_interface and do not declare their own data() member function, but they cannot use the default implementation, because their iterator types never satisfy contiguous_iterator:
-
std::ranges::basic_istream_view -
std::ranges::elements_view -
std::ranges::filter_view -
std::ranges::iota_view -
std::ranges::join_view -
std::ranges::lazy_split_view -
std::ranges::reverse_view -
std::ranges::split_view -
std::ranges::transform_view
Example
#include <array>
#include <iostream>
#include <ranges>
#include <string_view>
int main() {
constexpr std::string_view str { "Hello, C++20!" };
std::cout << (str | std::views::drop(7)).data() << '\n';
constexpr static std::array a { 1,2,3,4,5 };
constexpr auto v { a | std::views::take(3) };
static_assert( &a[0] == v.data() );
}
Output:
C++20!
See also
|
(C++17)
|
obtains the pointer to the underlying array (function template) |
|
(C++20)
|
obtains a pointer to the beginning of a contiguous range (customization point object) |
|
(C++20)
|
obtains a pointer to the beginning of a read-only contiguous range (customization point object) |
|
(C++20)
|
obtains a raw pointer from a pointer-like type (function template) |
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